16 files changed, 295 insertions, 242 deletions
diff --git a/guides/bug_report_templates/active_record_master.rb b/guides/bug_report_templates/active_record_master.rb
index d95354e12d..2435444dc9 100644
--- a/guides/bug_report_templates/active_record_master.rb
+++ b/guides/bug_report_templates/active_record_master.rb
@@ -2,7 +2,6 @@ unless File.exist?('Gemfile')
   File.write('Gemfile', <<-GEMFILE)
     source 'https://rubygems.org'
     gem 'rails', github: 'rails/rails'
-    gem 'arel', github: 'rails/arel'
     gem 'sqlite3'
   GEMFILE
 
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index ee2b00aedb..1735188f27 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -260,7 +260,7 @@ used:
 params.require(:log_entry).permit!
 ```
 
-This will mark the `:log_entry` parameters hash and any subhash of it
+This will mark the `:log_entry` parameters hash and any sub-hash of it
 permitted. Extreme care should be taken when using `permit!` as it
 will allow all current and future model attributes to be
 mass-assigned.
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 834c94e2ec..5a4e15cfa9 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -761,7 +761,7 @@ Arguments may be bare constant names:
 Math.qualified_const_get("E") # => 2.718281828459045
 ```
 
-These methods are analogous to their builtin counterparts. In particular,
+These methods are analogous to their built-in counterparts. In particular,
 `qualified_constant_defined?` accepts an optional second argument to be
 able to say whether you want the predicate to look in the ancestors.
 This flag is taken into account for each constant in the expression while
@@ -792,7 +792,7 @@ N.qualified_const_defined?("C::X")        # => true
 As the last example implies, the second argument defaults to true,
 as in `const_defined?`.
 
-For coherence with the builtin methods only relative paths are accepted.
+For coherence with the built-in methods only relative paths are accepted.
 Absolute qualified constant names like `::Math::PI` raise `NameError`.
 
 NOTE: Defined in `active_support/core_ext/module/qualified_const.rb`.
@@ -2910,7 +2910,7 @@ NOTE: Defined in `active_support/core_ext/hash/indifferent_access.rb`.
 
 ### Compacting
 
-The methods `compact` and `compact!` return a Hash without items with `nil` value. 
+The methods `compact` and `compact!` return a Hash without items with `nil` value.
 
 ```ruby
 {a: 1, b: 2, c: nil}.compact # => {a: 1, b: 2}
@@ -3837,7 +3837,7 @@ rescue NameError => e
 end
 ```
 
-NOTE: Defined in `actionpack/lib/abstract_controller/helpers.rb`.
+NOTE: Defined in `active_support/core_ext/name_error.rb`.
 
 Extensions to `LoadError`
 -------------------------
@@ -3860,4 +3860,4 @@ rescue NameError => e
 end
 ```
 
-NOTE: Defined in `actionpack/lib/abstract_controller/helpers.rb`.
+NOTE: Defined in `active_support/core_ext/load_error.rb`.
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index d3dc790500..52fc9726d9 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -56,11 +56,11 @@ the comment operator on that line to later enable the asset pipeline:
 
 To set asset compression methods, set the appropriate configuration options
 in `production.rb` - `config.assets.css_compressor` for your CSS and
-`config.assets.js_compressor` for your Javascript:
+`config.assets.js_compressor` for your JavaScript:
 
 ```ruby
 config.assets.css_compressor = :yui
-config.assets.js_compressor = :uglify
+config.assets.js_compressor = :uglifier
 ```
 
 NOTE: The `sass-rails` gem is automatically used for CSS compression if included
@@ -766,7 +766,7 @@ exception indicating the name of the missing file(s).
 
 #### Far-future Expires Header
 
-Precompiled assets exist on the filesystem and are served directly by your web
+Precompiled assets exist on the file system and are served directly by your web
 server. They do not have far-future headers by default, so to get the benefit of
 fingerprinting you'll have to update your server configuration to add those
 headers.
diff --git a/guides/source/command_line.md b/guides/source/command_line.md
index 57283f7c40..756c8f8b51 100644
--- a/guides/source/command_line.md
+++ b/guides/source/command_line.md
@@ -254,7 +254,7 @@ $ rails generate scaffold HighScore game:string score:integer
 
 The generator checks that there exist the directories for models, controllers, helpers, layouts, functional and unit tests, stylesheets, creates the views, controller, model and database migration for HighScore (creating the `high_scores` table and fields), takes care of the route for the **resource**, and new tests for everything.
 
-The migration requires that we **migrate**, that is, run some Ruby code (living in that `20130717151933_create_high_scores.rb`) to modify the schema of our database. Which database? The sqlite3 database that Rails will create for you when we run the `rake db:migrate` command. We'll talk more about Rake in-depth in a little while.
+The migration requires that we **migrate**, that is, run some Ruby code (living in that `20130717151933_create_high_scores.rb`) to modify the schema of our database. Which database? The SQLite3 database that Rails will create for you when we run the `rake db:migrate` command. We'll talk more about Rake in-depth in a little while.
 
 ```bash
 $ rake db:migrate
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index f8f9e9cbd9..ae382fc54d 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -56,7 +56,7 @@ These configuration methods are to be called on a `Rails::Railtie` object, such
     end
     ```
 
-* `config.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets, or when you want to work around the concurrency constraints builtin in browsers using different domain aliases. Shorter version of `config.action_controller.asset_host`.
+* `config.asset_host` sets the host for the assets. Useful when CDNs are used for hosting assets, or when you want to work around the concurrency constraints built-in in browsers using different domain aliases. Shorter version of `config.action_controller.asset_host`.
 
 * `config.autoload_once_paths` accepts an array of paths from which Rails will autoload constants that won't be wiped per request. Relevant if `config.cache_classes` is false, which is the case in development mode by default. Otherwise, all autoloading happens only once. All elements of this array must also be in `autoload_paths`. Default is an empty array.
 
@@ -644,11 +644,9 @@ development:
   encoding: unicode
   database: blog_development
   pool: 5
-  username: blog
-  password:
 ```
 
-Prepared Statements can be disabled thus:
+Prepared Statements are enabled by default on PostgreSQL. You can be disable prepared statements by setting `prepared_statements` to `false`:
 
 ```yaml
 production:
@@ -656,6 +654,16 @@ production:
   prepared_statements: false
 ```
 
+If enabled, Active Record will create up to `1000` prepared statements per database connection by default. To modify this behavior you can set `statement_limit` to a different value:
+
+```
+production:
+  adapter: postgresql
+  statement_limit: 200
+```
+
+The more prepared statements in use: the more memory your database will require. If your PostgreSQL database is hitting memory limits, try lowering `statement_limit` or disabling prepared statements.
+
 #### Configuring an SQLite3 Database for JRuby Platform
 
 If you choose to use SQLite3 and are using JRuby, your `config/database.yml` will look a little different. Here's the development section:
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 36e3862c6b..90c83a5e05 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -50,7 +50,7 @@ Please don't put "feature request" items into GitHub Issues. If there's a new
 feature that you want to see added to Ruby on Rails, you'll need to write the
 code yourself - or convince someone else to partner with you to write the code.
 Later in this guide you'll find detailed instructions for proposing a patch to
-Ruby on Rails. If you enter a wishlist item in GitHub Issues with no code, you
+Ruby on Rails. If you enter a wish list item in GitHub Issues with no code, you
 can expect it to be marked "invalid" as soon as it's reviewed.
 
 Sometimes, the line between 'bug' and 'feature' is a hard one to draw.
@@ -69,89 +69,6 @@ won't be accepted." But it's the proper place to discuss new ideas. GitHub
 Issues are not a particularly good venue for the sometimes long and involved
 discussions new features require.
 
-Setting Up a Development Environment
-------------------------------------
-
-To move on from submitting bugs to helping resolve existing issues or contributing your own code to Ruby on Rails, you _must_ be able to run its test suite. In this section of the guide you'll learn how to set up the tests on your own computer.
-
-### The Easy Way
-
-The easiest and recommended way to get a development environment ready to hack is to use the [Rails development box](https://github.com/rails/rails-dev-box).
-
-### The Hard Way
-
-In case you can't use the Rails development box, see section above, check [this other guide](development_dependencies_install.html).
-
-
-Running an Application Against Your Local Branch
-------------------------------------------------
-
-The `--dev` flag of `rails new` generates an application that uses your local
-branch:
-
-```bash
-$ cd rails
-$ bundle exec rails new ~/my-test-app --dev
-```
-
-The application generated in `~/my-test-app` runs against your local branch
-and in particular sees any modifications upon server reboot.
-
-
-Testing Active Record
----------------------
-
-This is how you run the Active Record test suite only for SQLite3:
-
-```bash
-$ cd activerecord
-$ bundle exec rake test_sqlite3
-```
-
-You can now run the tests as you did for `sqlite3`. The tasks are respectively
-
-```bash
-test_mysql
-test_mysql2
-test_postgresql
-```
-
-Finally,
-
-```bash
-$ bundle exec rake test
-```
-
-will now run the four of them in turn.
-
-You can also run any single test separately:
-
-```bash
-$ ARCONN=sqlite3 ruby -Itest test/cases/associations/has_many_associations_test.rb
-```
-
-You can invoke `test_jdbcmysql`, `test_jdbcsqlite3` or `test_jdbcpostgresql` also. See the file `activerecord/RUNNING_UNIT_TESTS.rdoc` for information on running more targeted database tests, or the file `ci/travis.rb` for the test suite run by the continuous integration server.
-
-### Warnings
-
-The test suite runs with warnings enabled. Ideally, Ruby on Rails should issue no warnings, but there may be a few, as well as some from third-party libraries. Please ignore (or fix!) them, if any, and submit patches that do not issue new warnings.
-
-If you are sure about what you are doing and would like to have a more clear output, there's a way to override the flag:
-
-```bash
-$ RUBYOPT=-W0 bundle exec rake test
-```
-
-### Older Versions of Ruby on Rails
-
-If you want to add a fix to older versions of Ruby on Rails, you'll need to set up and switch to your own local tracking branch. Here is an example to switch to the 3-0-stable branch:
-
-```bash
-$ git branch --track 3-0-stable origin/3-0-stable
-$ git checkout 3-0-stable
-```
-
-TIP: You may want to [put your Git branch name in your shell prompt](http://qugstart.com/blog/git-and-svn/add-colored-git-branch-name-to-your-shell-prompt/) to make it easier to remember which version of the code you're working with.
 
 Helping to Resolve Existing Issues
 ----------------------------------
@@ -227,9 +144,21 @@ WARNING: Docrails has a very strict policy: no code can be touched whatsoever, n
 Contributing to the Rails Code
 ------------------------------
 
-### Clone the Rails Repository
+### Setting Up a Development Environment ###
+
+To move on from submitting bugs to helping resolve existing issues or contributing your own code to Ruby on Rails, you _must_ be able to run its test suite. In this section of the guide you'll learn how to setup the tests on your own computer.
+
+#### The Easy Way
+
+The easiest and recommended way to get a development environment ready to hack is to use the [Rails development box](https://github.com/rails/rails-dev-box).
+
+#### The Hard Way
+
+In case you can't use the Rails development box, see section above, check [this other guide](development_dependencies_install.html).
 
-The first thing you need to do to be able to contribute code is to clone the repository:
+### Clone the Rails Repository ###
+
+To be able to contribute code, you need to clone the Rails repository:
 
 ```bash
 $ git clone git://github.com/rails/rails.git
@@ -244,29 +173,31 @@ $ git checkout -b my_new_branch
 
 It doesn't matter much what name you use, because this branch will only exist on your local computer and your personal repository on GitHub. It won't be part of the Rails Git repository.
 
-### Write Your Code
+### Running an Application Against Your Local Branch ###
+
+In case you need a dummy Rails app to test changes, the `--dev` flag of `rails new` generates an application that uses your local branch:
+
+```bash
+$ cd rails
+$ bundle exec rails new ~/my-test-app --dev
+```
+
+The application generated in `~/my-test-app` runs against your local branch
+and in particular sees any modifications upon server reboot.
 
-Now get busy and add or edit code. You're on your branch now, so you can write whatever you want (you can check to make sure you're on the right branch with `git branch -a`). But if you're planning to submit your change back for inclusion in Rails, keep a few things in mind:
+### Write Your Code ###
+
+Now get busy and add/edit code. You're on your branch now, so you can write whatever you want (you can check to make sure you're on the right branch with `git branch -a`). But if you're planning to submit your change back for inclusion in Rails, keep a few things in mind:
 
 * Get the code right.
 * Use Rails idioms and helpers.
 * Include tests that fail without your code, and pass with it.
 * Update the (surrounding) documentation, examples elsewhere, and the guides: whatever is affected by your contribution.
 
-It is not customary in Rails to run the full test suite before pushing
-changes. The railties test suite in particular takes a long time, and even
-more if the source code is mounted in `/vagrant` as happens in the recommended
-workflow with the [rails-dev-box](https://github.com/rails/rails-dev-box).
-
-As a compromise, test what your code obviously affects, and if the change is
-not in railties, run the whole test suite of the affected component. If all
-tests are passing, that's enough to propose your contribution. We have
-[Travis CI](https://travis-ci.org/rails/rails) as a safety net for catching
-unexpected breakages elsewhere.
 
 TIP: Changes that are cosmetic in nature and do not add anything substantial to the stability, functionality, or testability of Rails will generally not be accepted.
 
-### Follow the Coding Conventions
+#### Follow the Coding Conventions
 
 Rails follows a simple set of coding style conventions:
 
@@ -284,7 +215,84 @@ Rails follows a simple set of coding style conventions:
 
 The above are guidelines - please use your best judgment in using them.
 
-### Updating the CHANGELOG
+### Running Tests ###
+It is not customary in Rails to run the full test suite before pushing
+changes. The railties test suite in particular takes a long time, and even
+more if the source code is mounted in `/vagrant` as happens in the recommended
+workflow with the [rails-dev-box](https://github.com/rails/rails-dev-box).
+
+As a compromise, test what your code obviously affects, and if the change is
+not in railties, run the whole test suite of the affected component. If all
+tests are passing, that's enough to propose your contribution. We have
+[Travis CI](https://travis-ci.org/rails/rails) as a safety net for catching
+unexpected breakages elsewhere.
+
+#### Entire Rails:
+To run all the tests, do:
+```bash
+$ cd rails
+$ bundle exec rake test
+```
+#### Particular component of Rails
+To run tests only for particular component(ActionPack, ActiveRecord, etc.). For
+example, to run `ActionMailer` tests you can:
+
+```bash
+$ cd actionmailer
+$ bundle exec rake test
+```
+
+##### Testing Active Record
+
+This is how you run the Active Record test suite only for SQLite3:
+
+```bash
+$ cd activerecord
+$ bundle exec rake test_sqlite3
+```
+
+You can now run the tests as you did for `sqlite3`. The tasks are respectively
+
+```bash
+test_mysql
+test_mysql2
+test_postgresql
+```
+
+Finally,
+
+```bash
+$ bundle exec rake test
+```
+
+will now run the four of them in turn.
+
+You can also run any single test separately:
+
+```bash
+$ ARCONN=sqlite3 ruby -Itest test/cases/associations/has_many_associations_test.rb
+```
+
+You can invoke `test_jdbcmysql`, `test_jdbcsqlite3` or `test_jdbcpostgresql` also. See the file `activerecord/RUNNING_UNIT_TESTS.rdoc` for information on running more targeted database tests, or the file `ci/travis.rb` for the test suite run by the continuous integration server.
+
+#### Single Test separately
+to run just one test. For example, to run `LayoutMailerTest` you can:
+
+```bash
+$ cd actionmailer
+$ ruby -w -Ilib:test test/mail_layout_test.rb
+```
+
+### Warnings ###
+
+The test suite runs with warnings enabled. Ideally, Ruby on Rails should issue no warnings, but there may be a few, as well as some from third-party libraries. Please ignore (or fix!) them, if any, and submit patches that do not issue new warnings.
+
+If you are sure about what you are doing and would like to have a more clear output, there's a way to override the flag:
+
+```bash
+$ RUBYOPT=-W0 bundle exec rake test
+```
+### Updating the CHANGELOG ###
 
 The CHANGELOG is an important part of every release. It keeps the list of changes for every Rails version.
 
@@ -309,17 +317,17 @@ A CHANGELOG entry should summarize what was changed and should end with author's
 
 Your name can be added directly after the last word if you don't provide any code examples or don't need multiple paragraphs. Otherwise, it's best to make as a new paragraph.
 
-### Sanity Check
+### Sanity Check ###
 
 You should not be the only person who looks at the code before you submit it.
 If you know someone else who uses Rails, try asking them if they'll check out
 your work. If you don't know anyone else using Rails, try hopping into the IRC
-room or posting about your idea to the rails-core mailing list.  Doing this in
-private before you push a patch out publicly is the “smoke test” for a patch:
-if you can’t convince one other developer of the beauty of your code, you’re
+room or posting about your idea to the rails-core mailing list. Doing this in
+private before you push a patch out publicly is the "smoke test" for a patch:
+if you can't convince one other developer of the beauty of your code, you’re
 unlikely to convince the core team either.
 
-### Commit Your Changes
+### Commit Your Changes ###
 
 When you're happy with the code on your computer, you need to commit the changes to Git:
 
@@ -359,7 +367,7 @@ You can also add bullet points:
 
 TIP. Please squash your commits into a single commit when appropriate. This simplifies future cherry picks, and also keeps the git log clean.
 
-### Update Your Branch
+### Update Your Branch ###
 
 It's pretty likely that other changes to master have happened while you were working. Go get them:
 
@@ -377,7 +385,7 @@ $ git rebase master
 
 No conflicts? Tests still pass? Change still seems reasonable to you? Then move on.
 
-### Fork
+### Fork ###
 
 Navigate to the Rails [GitHub repository](https://github.com/rails/rails) and press "Fork" in the upper right hand corner.
 
@@ -507,7 +515,19 @@ $ git push origin my_pull_request -f
 You should be able to refresh the pull request on GitHub and see that it has
 been updated.
 
-### Backporting
+
+### Older Versions of Ruby on Rails ###
+
+If you want to add a fix to older versions of Ruby on Rails, you'll need to set up and switch to your own local tracking branch. Here is an example to switch to the 3-0-stable branch:
+
+```bash
+$ git branch --track 3-0-stable origin/3-0-stable
+$ git checkout 3-0-stable
+```
+
+TIP: You may want to [put your Git branch name in your shell prompt](http://qugstart.com/blog/git-and-svn/add-colored-git-branch-name-to-your-shell-prompt/) to make it easier to remember which version of the code you're working with.
+
+#### Backporting
 
 Changes that are merged into master are intended for the next major release of Rails. Sometimes, it might be beneficial for your changes to propagate back to the maintenance releases for older stable branches. Generally, security fixes and bug fixes are good candidates for a backport, while new features and patches that introduce a change in behavior will not be accepted. When in doubt, it is best to consult a Rails team member before backporting your changes to avoid wasted effort.
 
diff --git a/guides/source/engines.md b/guides/source/engines.md
index bbd63bb892..8f9ba0995f 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -1052,6 +1052,16 @@ This tells the application that you still want to perform a `GET` request to the
 `index` action of this controller, but you want to use the engine's route to get
 there, rather than the application's one.
 
+Another way to do this is to assign the `@routes` instance variable to `Engine.routes` in your test setup:
+
+```ruby
+setup do
+  @routes = Engine.routes
+end
+```
+
+This will also ensure url helpers for the engine will work as expected in your tests.
+
 Improving engine functionality
 ------------------------------
 
diff --git a/guides/source/form_helpers.md b/guides/source/form_helpers.md
index 205e0f6b62..019e7d4cf5 100644
--- a/guides/source/form_helpers.md
+++ b/guides/source/form_helpers.md
@@ -1008,4 +1008,4 @@ As a convenience you can instead pass the symbol `:all_blank` which will create
 
 ### Adding Fields on the Fly
 
-Rather than rendering multiple sets of fields ahead of time you may wish to add them only when a user clicks on an 'Add new address' button. Rails does not provide any builtin support for this. When generating new sets of fields you must ensure the key of the associated array is unique - the current JavaScript date (milliseconds after the epoch) is a common choice.
+Rather than rendering multiple sets of fields ahead of time you may wish to add them only when a user clicks on an 'Add new address' button. Rails does not provide any built-in support for this. When generating new sets of fields you must ensure the key of the associated array is unique - the current JavaScript date (milliseconds after the epoch) is a common choice.
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index 36bbd1187c..542e402ca1 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -863,7 +863,7 @@ def index
 end
 ```
 
-And then finally, add view for this action, located at
+And then finally, add the view for this action, located at
 `app/views/articles/index.html.erb`:
 
 ```html+erb
@@ -1028,17 +1028,21 @@ something went wrong. To do that, you'll modify
 
 ```html+erb
 <%= form_for :article, url: articles_path do |f| %>
+
   <% if @article.errors.any? %>
-  <div id="error_explanation">
-    <h2><%= pluralize(@article.errors.count, "error") %> prohibited
-      this article from being saved:</h2>
-    <ul>
-    <% @article.errors.full_messages.each do |msg| %>
-      <li><%= msg %></li>
-    <% end %>
-    </ul>
-  </div>
+    <div id="error_explanation">
+      <h2>
+        <%= pluralize(@article.errors.count, "error") %> prohibited
+        this article from being saved:
+      </h2>
+      <ul>
+        <% @article.errors.full_messages.each do |msg| %>
+          <li><%= msg %></li>
+        <% end %>
+      </ul>
+    </div>
   <% end %>
+
   <p>
     <%= f.label :title %><br>
     <%= f.text_field :title %>
@@ -1052,6 +1056,7 @@ something went wrong. To do that, you'll modify
   <p>
     <%= f.submit %>
   </p>
+
 <% end %>
 
 <%= link_to 'Back', articles_path %>
@@ -1100,17 +1105,21 @@ it look as follows:
 <h1>Editing article</h1>
 
 <%= form_for :article, url: article_path(@article), method: :patch do |f| %>
+
   <% if @article.errors.any? %>
-  <div id="error_explanation">
-    <h2><%= pluralize(@article.errors.count, "error") %> prohibited
-      this article from being saved:</h2>
-    <ul>
-    <% @article.errors.full_messages.each do |msg| %>
-      <li><%= msg %></li>
-    <% end %>
-    </ul>
-  </div>
+    <div id="error_explanation">
+      <h2>
+        <%= pluralize(@article.errors.count, "error") %> prohibited
+        this article from being saved:
+      </h2>
+      <ul>
+        <% @article.errors.full_messages.each do |msg| %>
+          <li><%= msg %></li>
+        <% end %>
+      </ul>
+    </div>
   <% end %>
+
   <p>
     <%= f.label :title %><br>
     <%= f.text_field :title %>
@@ -1124,6 +1133,7 @@ it look as follows:
   <p>
     <%= f.submit %>
   </p>
+
 <% end %>
 
 <%= link_to 'Back', articles_path %>
@@ -1187,14 +1197,14 @@ it appear next to the "Show" link:
     <th colspan="2"></th>
   </tr>
 
-<% @articles.each do |article| %>
-  <tr>
-    <td><%= article.title %></td>
-    <td><%= article.text %></td>
-    <td><%= link_to 'Show', article_path(article) %></td>
-    <td><%= link_to 'Edit', edit_article_path(article) %></td>
-  </tr>
-<% end %>
+  <% @articles.each do |article| %>
+    <tr>
+      <td><%= article.title %></td>
+      <td><%= article.text %></td>
+      <td><%= link_to 'Show', article_path(article) %></td>
+      <td><%= link_to 'Edit', edit_article_path(article) %></td>
+    </tr>
+  <% end %>
 </table>
 ```
 
@@ -1228,17 +1238,21 @@ content:
 
 ```html+erb
 <%= form_for @article do |f| %>
+
   <% if @article.errors.any? %>
-  <div id="error_explanation">
-    <h2><%= pluralize(@article.errors.count, "error") %> prohibited
-      this article from being saved:</h2>
-    <ul>
-    <% @article.errors.full_messages.each do |msg| %>
-      <li><%= msg %></li>
-    <% end %>
-    </ul>
-  </div>
+    <div id="error_explanation">
+      <h2>
+        <%= pluralize(@article.errors.count, "error") %> prohibited
+        this article from being saved:
+      </h2>
+      <ul>
+        <% @article.errors.full_messages.each do |msg| %>
+          <li><%= msg %></li>
+        <% end %>
+      </ul>
+    </div>
   <% end %>
+
   <p>
     <%= f.label :title %><br>
     <%= f.text_field :title %>
@@ -1252,6 +1266,7 @@ content:
   <p>
     <%= f.submit %>
   </p>
+
 <% end %>
 ```
 
@@ -1333,16 +1348,17 @@ together.
     <th colspan="3"></th>
   </tr>
 
-<% @articles.each do |article| %>
-  <tr>
-    <td><%= article.title %></td>
-    <td><%= article.text %></td>
-    <td><%= link_to 'Show', article_path(article) %></td>
-    <td><%= link_to 'Edit', edit_article_path(article) %></td>
-    <td><%= link_to 'Destroy', article_path(article),
-                    method: :delete, data: { confirm: 'Are you sure?' } %></td>
-  </tr>
-<% end %>
+  <% @articles.each do |article| %>
+    <tr>
+      <td><%= article.title %></td>
+      <td><%= article.text %></td>
+      <td><%= link_to 'Show', article_path(article) %></td>
+      <td><%= link_to 'Edit', edit_article_path(article) %></td>
+      <td><%= link_to 'Destroy', article_path(article),
+              method: :delete,
+              data: { confirm: 'Are you sure?' } %></td>
+    </tr>
+  <% end %>
 </table>
 ```
 
@@ -1552,8 +1568,8 @@ So first, we'll wire up the Article show template
   </p>
 <% end %>
 
-<%= link_to 'Back', articles_path %>
-| <%= link_to 'Edit', edit_article_path(@article) %>
+<%= link_to 'Back', articles_path %> |
+<%= link_to 'Edit', edit_article_path(@article) %>
 ```
 
 This adds a form on the `Article` show page that creates a new comment by
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 466ffe7907..c1b575c7b7 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -92,7 +92,7 @@ Rails adds all `.rb` and `.yml` files from the `config/locales` directory to you
 
 The default `en.yml` locale in this directory contains a sample pair of translation strings:
 
-```ruby
+```yaml
 en:
   hello: "Hello world"
 ```
@@ -179,7 +179,7 @@ end
 # in your /etc/hosts file to try this out locally
 def extract_locale_from_tld
   parsed_locale = request.host.split('.').last
-  I18n.available_locales.include?(parsed_locale.to_sym) ? parsed_locale : nil
+  I18n.available_locales.map(&:to_s).include?(parsed_locale) ? parsed_locale : nil
 end
 ```
 
@@ -192,7 +192,7 @@ We can also set the locale from the _subdomain_ in a very similar way:
 # in your /etc/hosts file to try this out locally
 def extract_locale_from_subdomain
   parsed_locale = request.subdomains.first
-  I18n.available_locales.include?(parsed_locale.to_sym) ? parsed_locale : nil
+  I18n.available_locales.map(&:to_s).include?(parsed_locale) ? parsed_locale : nil
 end
 ```
 
@@ -369,7 +369,7 @@ NOTE: Rails adds a `t` (`translate`) helper method to your views so that you do
 
 So let's add the missing translations into the dictionary files (i.e. do the "localization" part):
 
-```ruby
+```yaml
 # config/locales/en.yml
 en:
   hello_world: Hello world!
@@ -421,7 +421,7 @@ OK! Now let's add a timestamp to the view, so we can demo the **date/time locali
 
 And in our pirate translations file let's add a time format (it's already there in Rails' defaults for English):
 
-```ruby
+```yaml
 # config/locales/pirate.yml
 pirate:
   time:
@@ -680,62 +680,13 @@ NOTE: Automatic conversion to HTML safe translate text is only available from th
 
 ![i18n demo html safe](images/i18n/demo_html_safe.png)
 
-How to Store your Custom Translations
--------------------------------------
-
-The Simple backend shipped with Active Support allows you to store translations in both plain Ruby and YAML format.[^2]
-
-For example a Ruby Hash providing translations can look like this:
-
-```ruby
-{
-  pt: {
-    foo: {
-      bar: "baz"
-    }
-  }
-}
-```
-
-The equivalent YAML file would look like this:
-
-```ruby
-pt:
-  foo:
-    bar: baz
-```
-
-As you see, in both cases the top level key is the locale. `:foo` is a namespace key and `:bar` is the key for the translation "baz".
-
-Here is a "real" example from the Active Support `en.yml` translations YAML file:
-
-```ruby
-en:
-  date:
-    formats:
-      default: "%Y-%m-%d"
-      short: "%b %d"
-      long: "%B %d, %Y"
-```
-
-So, all of the following equivalent lookups will return the `:short` date format `"%b %d"`:
-
-```ruby
-I18n.t 'date.formats.short'
-I18n.t 'formats.short', scope: :date
-I18n.t :short, scope: 'date.formats'
-I18n.t :short, scope: [:date, :formats]
-```
-
-Generally we recommend using YAML as a format for storing translations. There are cases, though, where you want to store Ruby lambdas as part of your locale data, e.g. for special date formats.
-
 ### Translations for Active Record Models
 
 You can use the methods `Model.model_name.human` and `Model.human_attribute_name(attribute)` to transparently look up translations for your model and attribute names.
 
 For example when you add the following translations:
 
-```ruby
+```yaml
 en:
   activerecord:
     models:
@@ -750,7 +701,7 @@ Then `User.model_name.human` will return "Dude" and `User.human_attribute_name("
 
 You can also set a plural form for model names, adding as following:
 
-```ruby
+```yaml
 en:
   activerecord:
     models:
@@ -920,6 +871,55 @@ Rails uses fixed strings and other localizations, such as format strings and oth
 
 * `Array#to_sentence` uses format settings as given in the [support.array](https://github.com/rails/rails/blob/master/activesupport/lib/active_support/locale/en.yml#L33) scope.
 
+How to Store your Custom Translations
+-------------------------------------
+
+The Simple backend shipped with Active Support allows you to store translations in both plain Ruby and YAML format.[^2]
+
+For example a Ruby Hash providing translations can look like this:
+
+```yaml
+{
+  pt: {
+    foo: {
+      bar: "baz"
+    }
+  }
+}
+```
+
+The equivalent YAML file would look like this:
+
+```yaml
+pt:
+  foo:
+    bar: baz
+```
+
+As you see, in both cases the top level key is the locale. `:foo` is a namespace key and `:bar` is the key for the translation "baz".
+
+Here is a "real" example from the Active Support `en.yml` translations YAML file:
+
+```yaml
+en:
+  date:
+    formats:
+      default: "%Y-%m-%d"
+      short: "%b %d"
+      long: "%B %d, %Y"
+```
+
+So, all of the following equivalent lookups will return the `:short` date format `"%b %d"`:
+
+```ruby
+I18n.t 'date.formats.short'
+I18n.t 'formats.short', scope: :date
+I18n.t :short, scope: 'date.formats'
+I18n.t :short, scope: [:date, :formats]
+```
+
+Generally we recommend using YAML as a format for storing translations. There are cases, though, where you want to store Ruby lambdas as part of your locale data, e.g. for special date formats.
+
 Customize your I18n Setup
 -------------------------
 
diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index 77f3615ca0..00b2761716 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -587,7 +587,7 @@ def run_initializers(group=:default, *args)
 end
 ```
 
-The run_initializers code itself is tricky. What Rails is doing here is
+The `run_initializers` code itself is tricky. What Rails is doing here is
 traversing all the class ancestors looking for those that respond to an
 `initializers` method. It then sorts the ancestors by name, and runs them.
 For example, the `Engine` class will make all the engines available by
@@ -642,7 +642,7 @@ def build_app(app)
 end
 ```
 
-Remember, `build_app` was called (by wrapped_app) in the last line of `Server#start`.
+Remember, `build_app` was called (by `wrapped_app`) in the last line of `Server#start`.
 Here's how it looked like when we left:
 
 ```ruby
diff --git a/guides/source/migrations.md b/guides/source/migrations.md
index bfee55a95d..c61ccfe94a 100644
--- a/guides/source/migrations.md
+++ b/guides/source/migrations.md
@@ -495,6 +495,7 @@ class ExampleMigration < ActiveRecord::Migration
     add_column :users, :home_page_url, :string
     rename_column :users, :email, :email_address
   end
+end
 ```
 
 Using `reversible` will ensure that the instructions are executed in the
diff --git a/guides/source/nested_model_forms.md b/guides/source/nested_model_forms.md
index 855fab18e3..4f0634d955 100644
--- a/guides/source/nested_model_forms.md
+++ b/guides/source/nested_model_forms.md
@@ -17,9 +17,9 @@ Model setup
 
 To be able to use the nested model functionality in your forms, the model will need to support some basic operations.
 
-First of all, it needs to define a writer method for the attribute that corresponds to the association you are building a nested model form for. The `fields_for` form helper will look for this method to decide whether or not a nested model form should be build.
+First of all, it needs to define a writer method for the attribute that corresponds to the association you are building a nested model form for. The `fields_for` form helper will look for this method to decide whether or not a nested model form should be built.
 
-If the associated object is an array a form builder will be yielded for each object, else only a single form builder will be yielded.
+If the associated object is an array, a form builder will be yielded for each object, else only a single form builder will be yielded.
 
 Consider a Person model with an associated Address. When asked to yield a nested FormBuilder for the `:address` attribute, the `fields_for` form helper will look for a method on the Person instance named `address_attributes=`.
 
@@ -220,6 +220,6 @@ As you can see it has generated 2 `project name` inputs, one for each new `proje
 
 You can basically see the `projects_attributes` hash as an array of attribute hashes, one for each model instance.
 
-NOTE: The reason that `fields_for` constructed a form which would result in a hash instead of an array is that it won't work for any forms nested deeper than one level deep.
+NOTE: The reason that `fields_for` constructed a hash instead of an array is that it won't work for any form nested deeper than one level deep.
 
 TIP: You _can_ however pass an array to the writer method generated by `accepts_nested_attributes_for` if you're using plain Ruby or some other API access. See (TODO) for more info and example.
diff --git a/guides/source/security.md b/guides/source/security.md
index 15b28664b7..0d347c9e4b 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -60,7 +60,7 @@ Many web applications have an authentication system: a user provides a user name
 
 Hence, the cookie serves as temporary authentication for the web application. Anyone who seizes a cookie from someone else, may use the web application as this user - with possibly severe consequences. Here are some ways to hijack a session, and their countermeasures:
 
-* Sniff the cookie in an insecure network. A wireless LAN can be an example of such a network. In an unencrypted wireless LAN it is especially easy to listen to the traffic of all connected clients. This is one more reason not to work from a coffee shop. For the web application builder this means to _provide a secure connection over SSL_. In Rails 3.1 and later, this could be accomplished by always forcing SSL connection in your application config file:
+* Sniff the cookie in an insecure network. A wireless LAN can be an example of such a network. In an unencrypted wireless LAN it is especially easy to listen to the traffic of all connected clients. For the web application builder this means to _provide a secure connection over SSL_. In Rails 3.1 and later, this could be accomplished by always forcing SSL connection in your application config file:
 
     ```ruby
     config.force_ssl = true
@@ -239,24 +239,23 @@ Or the attacker places the code into the onmouseover event handler of an image:
 
 There are many other possibilities, like using a `<script>` tag to make a cross-site request to a URL with a JSONP or JavaScript response. The response is executable code that the attacker can find a way to run, possibly extracting sensitive data. To protect against this data leakage, we disallow cross-site `<script>` tags. Only Ajax requests may have JavaScript responses since XmlHttpRequest is subject to the browser Same-Origin policy - meaning only your site can initiate the request.
 
-To protect against all other forged requests, we introduce a _required security token_ that our site knows but other sites don't know. We include the security token in requests and verify it on the server. This is a one-liner in your application controller:
+To protect against all other forged requests, we introduce a _required security token_ that our site knows but other sites don't know. We include the security token in requests and verify it on the server. This is a one-liner in your application controller, and is the default for newly created rails applications:
 
 ```ruby
-protect_from_forgery
+protect_from_forgery with: :exception
 ```
 
-This will automatically include a security token in all forms and Ajax requests generated by Rails. If the security token doesn't match what was expected, the session will be reset.
+This will automatically include a security token in all forms and Ajax requests generated by Rails. If the security token doesn't match what was expected, an exception will be thrown.
 
 It is common to use persistent cookies to store user information, with `cookies.permanent` for example. In this case, the cookies will not be cleared and the out of the box CSRF protection will not be effective. If you are using a different cookie store than the session for this information, you must handle what to do with it yourself:
 
 ```ruby
-def handle_unverified_request
-  super
-  sign_out_user # Example method that will destroy the user cookies.
+rescue_from ActionController::InvalidAuthenticityToken do |exception|
+  sign_out_user # Example method that will destroy the user cookies
 end
 ```
 
-The above method can be placed in the `ApplicationController` and will be called when a CSRF token is not present on a non-GET request.
+The above method can be placed in the `ApplicationController` and will be called when a CSRF token is not present or is incorrect on a non-GET request.
 
 Note that _cross-site scripting (XSS) vulnerabilities bypass all CSRF protections_. XSS gives the attacker access to all elements on a page, so they can read the CSRF security token from a form or directly submit the form. Read <a href="#cross-site-scripting-xss">more about XSS</a> later.
 
diff --git a/guides/source/testing.md b/guides/source/testing.md
index aa37115d14..36d37f3af0 100644
--- a/guides/source/testing.md
+++ b/guides/source/testing.md
@@ -796,7 +796,7 @@ when you initiate a Rails project.
 Brief Note About `MiniTest`
 -----------------------------
 
-Ruby ships with a boat load of libraries. Ruby 1.8 provides `Test::Unit`, a framework for unit testing in Ruby. All the basic assertions discussed above are actually defined in `Test::Unit::Assertions`. The class `ActiveSupport::TestCase` which we have been using in our unit and functional tests extends `Test::Unit::TestCase`, allowing
+Ruby ships with a vast Standard Library for all common use-cases including testing. Ruby 1.8 provided `Test::Unit`, a framework for unit testing in Ruby. All the basic assertions discussed above are actually defined in `Test::Unit::Assertions`. The class `ActiveSupport::TestCase` which we have been using in our unit and functional tests extends `Test::Unit::TestCase`, allowing
 us to use all of the basic assertions in our tests.
 
 Ruby 1.9 introduced `MiniTest`, an updated version of `Test::Unit` which provides a backwards compatible API for `Test::Unit`. You could also use `MiniTest` in Ruby 1.8 by installing the `minitest` gem.