16 files changed, 67 insertions, 53 deletions
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index 73e6c2c05b..a30bfc458a 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -871,7 +871,7 @@ Please refer to the [Changelog][active-support] for detailed changes.
     `module Foo; extend ActiveSupport::Concern; end` boilerplate.
     ([Commit](https://github.com/rails/rails/commit/b16c36e688970df2f96f793a759365b248b582ad))
 
-*   New [guide](constant_autoloading_and_reloading.html) about constant autoloading and reloading.
+*   New [guide](autoloading_and_reloading_constants.html) about constant autoloading and reloading.
 
 Credits
 -------
diff --git a/guides/source/5_0_release_notes.md b/guides/source/5_0_release_notes.md
index 638547565c..a07ce7e859 100644
--- a/guides/source/5_0_release_notes.md
+++ b/guides/source/5_0_release_notes.md
@@ -50,7 +50,7 @@ ToDo...
 
 Defines an attribute with a type on a model. It will override the type of existing attributes if needed. 
 This allows control over how values are converted to and from SQL when assigned to a model.
-It also changes the behavior of values passed to ActiveRecord::Base.where, which lets use our domain objects across much of Active Record, 
+It also changes the behavior of values passed to `ActiveRecord::Base.where`, which lets use our domain objects across much of Active Record,
 without having to rely on implementation details or monkey patching.
 
 Some things that you can achieve with this:
diff --git a/guides/source/action_cable_overview.md b/guides/source/action_cable_overview.md
index c7770c16ea..16aa9438a2 100644
--- a/guides/source/action_cable_overview.md
+++ b/guides/source/action_cable_overview.md
@@ -82,7 +82,7 @@ The cookie is then automatically sent to the connection instance when a new conn
 is attempted, and you use that to set the `current_user`. By identifying the connection
 by this same current user, you're also ensuring that you can later retrieve all open
 connections by a given user (and potentially disconnect them all if the user is deleted
-or deauthorized).
+or unauthorized).
 
 ### Channels
 
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index a906f64633..e6cd00728d 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -21,7 +21,7 @@ After reading this guide, you will know:
 What Does a Controller Do?
 --------------------------
 
-Action Controller is the C in MVC. After routing has determined which controller to use for a request, the controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
+Action Controller is the C in MVC. After the router has determined which controller to use for a request, the controller is responsible for making sense of the request and producing the appropriate output. Luckily, Action Controller does most of the groundwork for you and uses smart conventions to make this as straightforward as possible.
 
 For most conventional [RESTful](http://en.wikipedia.org/wiki/Representational_state_transfer) applications, the controller will receive the request (this is invisible to you as the developer), fetch or save data from a model and use a view to create HTML output. If your controller needs to do things a little differently, that's not a problem, this is just the most common way for a controller to work.
 
@@ -145,7 +145,7 @@ So for example, if you are sending this JSON content:
 
 Your controller will receive `params[:company]` as `{ "name" => "acme", "address" => "123 Carrot Street" }`.
 
-Also, if you've turned on `config.wrap_parameters` in your initializer or called `wrap_parameters` in your controller, you can safely omit the root element in the JSON parameter. In this case, the parameters will be cloned and wrapped with a key chosen based on your controller's name. So the above JSON POST can be written as:
+Also, if you've turned on `config.wrap_parameters` in your initializer or called `wrap_parameters` in your controller, you can safely omit the root element in the JSON parameter. In this case, the parameters will be cloned and wrapped with a key chosen based on your controller's name. So the above JSON request can be written as:
 
 ```json
 { "name": "acme", "address": "123 Carrot Street" }
@@ -199,7 +199,8 @@ practice to help prevent accidentally allowing users to update sensitive
 model attributes.
 
 In addition, parameters can be marked as required and will flow through a
-predefined raise/rescue flow to end up as a 400 Bad Request.
+predefined raise/rescue flow that will result in a 400 Bad Request being
+returned if not all required parameters are passed in.
 
 ```ruby
 class PeopleController < ActionController::Base
@@ -213,8 +214,8 @@ class PeopleController < ActionController::Base
   # This will pass with flying colors as long as there's a person key
   # in the parameters, otherwise it'll raise a
   # ActionController::ParameterMissing exception, which will get
-  # caught by ActionController::Base and turned into that 400 Bad
-  # Request reply.
+  # caught by ActionController::Base and turned into a 400 Bad
+  # Request error.
   def update
     person = current_account.people.find(params[:id])
     person.update!(person_params)
diff --git a/guides/source/action_mailer_basics.md b/guides/source/action_mailer_basics.md
index 5346b7c32b..7359438025 100644
--- a/guides/source/action_mailer_basics.md
+++ b/guides/source/action_mailer_basics.md
@@ -734,7 +734,7 @@ files (environment.rb, production.rb, etc...)
 | Configuration | Description |
 |---------------|-------------|
 |`logger`|Generates information on the mailing run if available. Can be set to `nil` for no logging. Compatible with both Ruby's own `Logger` and `Log4r` loggers.|
-|`smtp_settings`|Allows detailed configuration for `:smtp` delivery method:<ul><li>`:address` - Allows you to use a remote mail server. Just change it from its default `"localhost"` setting.</li><li>`:port` - On the off chance that your mail server doesn't run on port 25, you can change it.</li><li>`:domain` - If you need to specify a HELO domain, you can do it here.</li><li>`:user_name` - If your mail server requires authentication, set the username in this setting.</li><li>`:password` - If your mail server requires authentication, set the password in this setting.</li><li>`:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain` (will send the password in the clear), `:login` (will send password Base64 encoded) or `:cram_md5` (combines a Challenge/Response mechanism to exchange information and a cryptographic Message Digest 5 algorithm to hash important information)</li><li>`:enable_starttls_auto` - Detects if STARTTLS is enabled in your SMTP server and starts to use it. Defaults to `true`.</li><li>`:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is really useful if you need to validate a self-signed and/or a wildcard certificate. You can use the name of an OpenSSL verify constant ('none', 'peer', 'client_once', 'fail_if_no_peer_cert') or directly the constant (`OpenSSL::SSL::VERIFY_NONE`, `OpenSSL::SSL::VERIFY_PEER`, ...).</li></ul>|
+|`smtp_settings`|Allows detailed configuration for `:smtp` delivery method:<ul><li>`:address` - Allows you to use a remote mail server. Just change it from its default `"localhost"` setting.</li><li>`:port` - On the off chance that your mail server doesn't run on port 25, you can change it.</li><li>`:domain` - If you need to specify a HELO domain, you can do it here.</li><li>`:user_name` - If your mail server requires authentication, set the username in this setting.</li><li>`:password` - If your mail server requires authentication, set the password in this setting.</li><li>`:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain` (will send the password in the clear), `:login` (will send password Base64 encoded) or `:cram_md5` (combines a Challenge/Response mechanism to exchange information and a cryptographic Message Digest 5 algorithm to hash important information)</li><li>`:enable_starttls_auto` - Detects if STARTTLS is enabled in your SMTP server and starts to use it. Defaults to `true`.</li><li>`:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is really useful if you need to validate a self-signed and/or a wildcard certificate. You can use the name of an OpenSSL verify constant ('none' or 'peer') or directly the constant (`OpenSSL::SSL::VERIFY_NONE` or `OpenSSL::SSL::VERIFY_PEER`).</li></ul>|
 |`sendmail_settings`|Allows you to override options for the `:sendmail` delivery method.<ul><li>`:location` - The location of the sendmail executable. Defaults to `/usr/sbin/sendmail`.</li><li>`:arguments` - The command line arguments to be passed to sendmail. Defaults to `-i -t`.</li></ul>|
 |`raise_delivery_errors`|Whether or not errors should be raised if the email fails to be delivered. This only works if the external email server is configured for immediate delivery.|
 |`delivery_method`|Defines a delivery method. Possible values are:<ul><li>`:smtp` (default), can be configured by using `config.action_mailer.smtp_settings`.</li><li>`:sendmail`, can be configured by using `config.action_mailer.sendmail_settings`.</li><li>`:file`: save emails to files; can be configured by using `config.action_mailer.file_settings`.</li><li>`:test`: save emails to `ActionMailer::Base.deliveries` array.</li></ul>See [API docs](http://api.rubyonrails.org/classes/ActionMailer/Base.html) for more info.|
diff --git a/guides/source/action_view_overview.md b/guides/source/action_view_overview.md
index 0e6bb76101..f68abbae3c 100644
--- a/guides/source/action_view_overview.md
+++ b/guides/source/action_view_overview.md
@@ -15,7 +15,7 @@ After reading this guide, you will know:
 What is Action View?
 --------------------
 
-In Rails, web requests are handled by [Action Controller](action_controller_overview.html) and Action View. Typically, Action Controller will be concerned with communicating with the database and performing CRUD actions where necessary. Action View is then responsible for compiling the response.
+In Rails, web requests are handled by [Action Controller](action_controller_overview.html) and Action View. Typically, Action Controller is concerned with communicating with the database and performing CRUD actions where necessary. Action View is then responsible for compiling the response.
 
 Action View templates are written using embedded Ruby in tags mingled with HTML. To avoid cluttering the templates with boilerplate code, a number of helper classes provide common behavior for forms, dates, and strings. It's also easy to add new helpers to your application as it evolves.
 
diff --git a/guides/source/api_app.md b/guides/source/api_app.md
index 485294dc02..f373d313cc 100644
--- a/guides/source/api_app.md
+++ b/guides/source/api_app.md
@@ -212,6 +212,7 @@ An API application comes with the following middleware by default:
 - `ActionDispatch::RemoteIp`
 - `ActionDispatch::Reloader`
 - `ActionDispatch::Callbacks`
+- `ActiveRecord::Migration::CheckPending`
 - `Rack::Head`
 - `Rack::ConditionalGet`
 - `Rack::ETag`
@@ -339,7 +340,7 @@ API application, especially if one of your API clients is the browser:
 - `Rack::MethodOverride`
 - `ActionDispatch::Cookies`
 - `ActionDispatch::Flash`
-- For sessions management
+- For session management
     * `ActionDispatch::Session::CacheStore`
     * `ActionDispatch::Session::CookieStore`
     * `ActionDispatch::Session::MemCacheStore`
@@ -373,10 +374,8 @@ controller modules by default:
 - `AbstractController::Rendering` and `ActionController::ApiRendering`: Basic support for rendering.
 - `ActionController::Renderers::All`: Support for `render :json` and friends.
 - `ActionController::ConditionalGet`: Support for `stale?`.
-- `ActionController::BasicImplicitRender`: Makes sure to return an empty response
-  if there's not an explicit one.
-- `ActionController::StrongParameters`: Support for parameters white-listing in
-  combination with Active Model mass assignment.
+- `ActionController::BasicImplicitRender`: Makes sure to return an empty response, if there isn't an explicit one.
+- `ActionController::StrongParameters`: Support for parameters white-listing in combination with Active Model mass assignment.
 - `ActionController::ForceSSL`: Support for `force_ssl`.
 - `ActionController::DataStreaming`: Support for `send_file` and `send_data`.
 - `AbstractController::Callbacks`: Support for `before_action` and
@@ -386,8 +385,8 @@ controller modules by default:
   hooks defined by Action Controller (see [the instrumentation
   guide](active_support_instrumentation.html#action-controller) for
 more information regarding this).
-- `ActionController::ParamsWrapper`: Wraps the parameters hash into a nested hash
-  so you don't have to specify root elements sending POST requests for instance.
+- `ActionController::ParamsWrapper`: Wraps the parameters hash into a nested hash, 
+  so that you don't have to specify root elements sending POST requests for instance.
 
 Other plugins may add additional modules. You can get a list of all modules
 included into `ActionController::API` in the rails console:
diff --git a/guides/source/command_line.md b/guides/source/command_line.md
index 0e6d119681..f766403228 100644
--- a/guides/source/command_line.md
+++ b/guides/source/command_line.md
@@ -433,7 +433,7 @@ Ruby version              2.2.2 (x86_64-linux)
 RubyGems version          2.4.6
 Rack version              1.6
 JavaScript Runtime        Node.js (V8)
-Middleware                Rack::Sendfile, ActionDispatch::Static, ActionDispatch::Executor, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActiveRecord::ConnectionAdapters::ConnectionManagement, ActiveRecord::QueryCache, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag
+Middleware                Rack::Sendfile, ActionDispatch::Static, ActionDispatch::Executor, #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x007ffd131a7c88>, Rack::Runtime, Rack::MethodOverride, ActionDispatch::RequestId, Rails::Rack::Logger, ActionDispatch::ShowExceptions, ActionDispatch::DebugExceptions, ActionDispatch::RemoteIp, ActionDispatch::Reloader, ActionDispatch::Callbacks, ActiveRecord::Migration::CheckPending, ActionDispatch::Cookies, ActionDispatch::Session::CookieStore, ActionDispatch::Flash, Rack::Head, Rack::ConditionalGet, Rack::ETag
 Application root          /home/foobar/commandsapp
 Environment               development
 Database adapter          sqlite3
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 66aae112d8..b3d3b2c681 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -224,8 +224,6 @@ Every Rails application comes with a standard set of middleware which it uses in
 * `ActionDispatch::RemoteIp` checks for IP spoofing attacks and gets valid `client_ip` from request headers. Configurable with the `config.action_dispatch.ip_spoofing_check`, and `config.action_dispatch.trusted_proxies` options.
 * `Rack::Sendfile` intercepts responses whose body is being served from a file and replaces it with a server specific X-Sendfile header. Configurable with `config.action_dispatch.x_sendfile_header`.
 * `ActionDispatch::Callbacks` runs the prepare callbacks before serving the request.
-* `ActiveRecord::ConnectionAdapters::ConnectionManagement` cleans active connections after each request, unless the `rack.test` key in the request environment is set to `true`.
-* `ActiveRecord::QueryCache` caches all SELECT queries generated in a request. If any INSERT or UPDATE takes place then the cache is cleaned.
 * `ActionDispatch::Cookies` sets cookies for the request.
 * `ActionDispatch::Session::CookieStore` is responsible for storing the session in cookies. An alternate middleware can be used for this by changing the `config.action_controller.session_store` to an alternate value. Additionally, options passed to this can be configured by using `config.action_controller.session_options`.
 * `ActionDispatch::Flash` sets up the `flash` keys. Only available if `config.action_controller.session_store` is set to a value.
@@ -244,6 +242,12 @@ This will put the `Magical::Unicorns` middleware on the end of the stack. You ca
 config.middleware.insert_before Rack::Head, Magical::Unicorns
 ```
 
+Or you can insert a middleware to exact position by using indexes. For example, if you want to insert `Magical::Unicorns` middleware on top of the stack, you can do it, like so:
+
+```ruby
+config.middleware.insert_before 0, Magical::Unicorns
+```
+
 There's also `insert_after` which will insert a middleware after another:
 
 ```ruby
@@ -274,6 +278,26 @@ All these configuration options are delegated to the `I18n` library.
 
 * `config.i18n.load_path` sets the path Rails uses to look for locale files. Defaults to `config/locales/*.{yml,rb}`.
 
+* `config.i18n.fallbacks` sets fallback behavior for missing translations. Here are 3 usage examples for this option:
+
+  * You can set the option to `true` for using default locale as fallback, like so:
+
+    ```ruby
+    config.i18n.fallbacks = true
+    ```
+
+  * Or you can set an array of locales as fallback, like so:
+
+    ```ruby
+    config.i18n.fallbacks = [:tr, :en]
+    ```
+
+  * Or you can set different fallbacks for locales individually. For example, if you want to use `:tr` for `:az` and `:de`, `:en` for `:da` as fallbacks, you can do it, like so:
+
+    ```ruby
+    config.i18n.fallbacks = { az: :tr, da: [:de, :en] }
+    ```
+
 ### Configuring Active Record
 
 `config.active_record` includes a variety of configuration options:
@@ -500,7 +524,7 @@ There are a number of settings available on `config.action_mailer`:
     * `:password` - If your mail server requires authentication, set the password in this setting.
     * `:authentication` - If your mail server requires authentication, you need to specify the authentication type here. This is a symbol and one of `:plain`, `:login`, `:cram_md5`.
     * `:enable_starttls_auto` - Detects if STARTTLS is enabled in your SMTP server and starts to use it. It defaults to `true`.
-    * `:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is useful if you need to validate a self-signed and/or a wildcard certificate. This can be one of the OpenSSL verify constants, `:none`, `:peer`, `:client_once`, `:fail_if_no_peer_cert`, or the constant directly `OpenSSL::SSL::VERIFY_NONE`.
+    * `:openssl_verify_mode` - When using TLS, you can set how OpenSSL checks the certificate. This is useful if you need to validate a self-signed and/or a wildcard certificate. This can be one of the OpenSSL verify constants, `:none` or `:peer` -- or the constant directly `OpenSSL::SSL::VERIFY_NONE` or `OpenSSL::SSL::VERIFY_PEER`, respectively.
     * `:ssl/:tls` - Enables the SMTP connection to use SMTP/TLS (SMTPS: SMTP over direct TLS connection).                                  
 
 * `config.action_mailer.sendmail_settings` allows detailed configuration for the `sendmail` delivery method. It accepts a hash of options, which can include any of these options:
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 59c902e148..ba8d085f79 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -25,7 +25,7 @@ Reporting an Issue
 
 Ruby on Rails uses [GitHub Issue Tracking](https://github.com/rails/rails/issues) to track issues (primarily bugs and contributions of new code). If you've found a bug in Ruby on Rails, this is the place to start. You'll need to create a (free) GitHub account in order to submit an issue, to comment on them or to create pull requests.
 
-NOTE: Bugs in the most recent released version of Ruby on Rails are likely to get the most attention. Also, the Rails core team is always interested in feedback from those who can take the time to test _edge Rails_ (the code for the version of Rails that is currently under development). Later in this guide you'll find out how to get edge Rails for testing.
+NOTE: Bugs in the most recent released version of Ruby on Rails are likely to get the most attention. Also, the Rails core team is always interested in feedback from those who can take the time to test _edge Rails_ (the code for the version of Rails that is currently under development). Later in this guide, you'll find out how to get edge Rails for testing.
 
 ### Creating a Bug Report
 
@@ -58,7 +58,7 @@ WARNING: Please do not report security vulnerabilities with public GitHub issue
 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
+Later in this guide, you'll find detailed instructions for proposing a patch to
 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.
 
@@ -131,7 +131,7 @@ learn about Ruby on Rails, and the API, which serves as a reference.
 You can help improve the Rails guides by making them more coherent, consistent or readable, adding missing information, correcting factual errors, fixing typos, or bringing them up to date with the latest edge Rails.
 
 You can either open a pull request to [Rails](https://github.com/rails/rails) or
-ask the [Rails core team](http://rubyonrails.org/core) for commit access on
+ask the [Rails core team](http://rubyonrails.org/community/#core) for commit access on
 docrails if you contribute regularly.
 Please do not open pull requests in docrails, if you'd like to get feedback on your
 change, ask for it in [Rails](https://github.com/rails/rails) instead.
@@ -189,7 +189,7 @@ Contributing to the Rails Code
 
 ### 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.
+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
 
@@ -299,9 +299,9 @@ Please see the benchmark/ips [README](https://github.com/evanphx/benchmark-ips/b
 ### 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).
+changes. The railties test suite in particular takes a long time, and takes an
+especially long time 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
@@ -662,7 +662,7 @@ Changes that are merged into master are intended for the next major release of R
 
 For simple fixes, the easiest way to backport your changes is to [extract a diff from your changes in master and apply them to the target branch](http://ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git).
 
-First make sure your changes are the only difference between your current branch and master:
+First, make sure your changes are the only difference between your current branch and master:
 
 ```bash
 $ git log master..HEAD
diff --git a/guides/source/credits.html.erb b/guides/source/credits.html.erb
index 1d995581fa..511d76041b 100644
--- a/guides/source/credits.html.erb
+++ b/guides/source/credits.html.erb
@@ -64,7 +64,7 @@ Oscar Del Ben is a software engineer at <a href="http://www.wildfireapp.com/">Wi
 <% end %>
 
 <%= author('Pratik Naik', 'lifo') do %>
-  Pratik Naik is a Ruby on Rails developer at <a href="https://basecamp.com/">Basecamp</a> and also a member of the <a href="http://rubyonrails.org/core">Rails core team</a>. He maintains a blog at <a href="http://m.onkey.org">has_many :bugs, :through =&gt; :rails</a> and has a semi-active <a href="http://twitter.com/lifo">twitter account</a>.
+  Pratik Naik is a Ruby on Rails developer at <a href="https://basecamp.com/">Basecamp</a> and maintains a blog at <a href="http://m.onkey.org">has_many :bugs, :through =&gt; :rails</a>. He also has a semi-active <a href="http://twitter.com/lifo">twitter account</a>.
 <% end %>
 
 <%= author('Emilio Tagua', 'miloops') do %>
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index 0edfa072f8..f3802a142f 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -109,12 +109,11 @@ The **translations load path** (`I18n.load_path`) is an array of paths to files
 
 NOTE: The backend lazy-loads these translations when a translation is looked up for the first time. This backend can be swapped with something else even after translations have already been announced.
 
-The default `config/application.rb` file has instructions on how to add locales from another directory and how to set a different default locale.
+You can change the default locale as well as configure the translations load paths in `config/application.rb` as follows:
 
 ```ruby
-# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
-# config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
-# config.i18n.default_locale = :de
+  config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
+  config.i18n.default_locale = :de
 ```
 
 The load path must be specified before any translations are looked up. To change the default locale from an initializer instead of `config/application.rb`:
diff --git a/guides/source/layout.html.erb b/guides/source/layout.html.erb
index 6db76b528e..9abb863da6 100644
--- a/guides/source/layout.html.erb
+++ b/guides/source/layout.html.erb
@@ -111,7 +111,7 @@
           <%= link_to 'open an issue', 'https://github.com/rails/rails/issues' %>.
         </p>
         <p>And last but not least, any kind of discussion regarding Ruby on Rails
-          documentation is very welcome in the <%= link_to 'rubyonrails-docs mailing list', 'http://groups.google.com/group/rubyonrails-docs' %>.
+          documentation is very welcome in the <%= link_to 'rubyonrails-docs mailing list', 'https://groups.google.com/forum/#!forum/rubyonrails-docs' %>.
         </p>
       </div>
     </div>
diff --git a/guides/source/rails_application_templates.md b/guides/source/rails_application_templates.md
index 3b773d84f8..3e99ee7021 100644
--- a/guides/source/rails_application_templates.md
+++ b/guides/source/rails_application_templates.md
@@ -15,14 +15,14 @@ After reading this guide, you will know:
 Usage
 -----
 
-To apply a template, you need to provide the Rails generator with the location of the template you wish to apply using the -m option. This can either be a path to a file or a URL.
+To apply a template, you need to provide the Rails generator with the location of the template you wish to apply using the `-m` option. This can either be a path to a file or a URL.
 
 ```bash
 $ rails new blog -m ~/template.rb
 $ rails new blog -m http://example.com/template.rb
 ```
 
-You can use the task `app:template` to apply templates to an existing Rails application. The location of the template needs to be passed in to an environment variable named LOCATION. Again, this can either be path to a file or a URL.
+You can use the `app:template` Rake task to apply templates to an existing Rails application. The location of the template needs to be passed in via the LOCATION environment variable. Again, this can either be path to a file or a URL.
 
 ```bash
 $ bin/rails app:template LOCATION=~/template.rb
diff --git a/guides/source/rails_on_rack.md b/guides/source/rails_on_rack.md
index d67702f52e..8148f70c31 100644
--- a/guides/source/rails_on_rack.md
+++ b/guides/source/rails_on_rack.md
@@ -105,19 +105,18 @@ For a freshly generated Rails application, this might produce something like:
 use Rack::Sendfile
 use ActionDispatch::Static
 use ActionDispatch::Executor
-use #<ActiveSupport::Cache::Strategy::LocalCache::Middleware:0x000000029a0838>
+use ActiveSupport::Cache::Strategy::LocalCache::Middleware
 use Rack::Runtime
 use Rack::MethodOverride
 use ActionDispatch::RequestId
 use Rails::Rack::Logger
 use ActionDispatch::ShowExceptions
+use WebConsole::Middleware
 use ActionDispatch::DebugExceptions
 use ActionDispatch::RemoteIp
 use ActionDispatch::Reloader
 use ActionDispatch::Callbacks
 use ActiveRecord::Migration::CheckPending
-use ActiveRecord::ConnectionAdapters::ConnectionManagement
-use ActiveRecord::QueryCache
 use ActionDispatch::Cookies
 use ActionDispatch::Session::CookieStore
 use ActionDispatch::Flash
@@ -149,9 +148,9 @@ You can add a new middleware to the middleware stack using any of the following
 # Push Rack::BounceFavicon at the bottom
 config.middleware.use Rack::BounceFavicon
 
-# Add Lifo::Cache after ActiveRecord::QueryCache.
+# Add Lifo::Cache after ActionDispatch::Executor.
 # Pass { page_cache: false } argument to Lifo::Cache.
-config.middleware.insert_after ActiveRecord::QueryCache, Lifo::Cache, page_cache: false
+config.middleware.insert_after ActionDispatch::Executor, Lifo::Cache, page_cache: false
 ```
 
 #### Swapping a Middleware
@@ -267,14 +266,6 @@ Much of Action Controller's functionality is implemented as Middlewares. The fol
 
 * Checks pending migrations and raises `ActiveRecord::PendingMigrationError` if any migrations are pending.
 
-**`ActiveRecord::ConnectionAdapters::ConnectionManagement`**
-
-* Cleans active connections after each request, unless the `rack.test` key in the request environment is set to `true`.
-
-**`ActiveRecord::QueryCache`**
-
-* Enables the Active Record query cache.
-
 **`ActionDispatch::Cookies`**
 
 * Sets cookies for the request.
diff --git a/guides/source/routing.md b/guides/source/routing.md
index 81321c7405..756e0fefd7 100644
--- a/guides/source/routing.md
+++ b/guides/source/routing.md
@@ -9,16 +9,16 @@ After reading this guide, you will know:
 
 * How to interpret the code in `config/routes.rb`.
 * How to construct your own routes, using either the preferred resourceful style or the `match` method.
-* What parameters to expect an action to receive.
+* How to declare route parameters, which are passed onto controller actions.
 * How to automatically create paths and URLs using route helpers.
-* Advanced techniques such as constraints and Rack endpoints.
+* Advanced techniques such as creating constraints and mounting Rack endpoints.
 
 --------------------------------------------------------------------------------
 
 The Purpose of the Rails Router
 -------------------------------
 
-The Rails router recognizes URLs and dispatches them to a controller's action. It can also generate paths and URLs, avoiding the need to hardcode strings in your views.
+The Rails router recognizes URLs and dispatches them to a controller's action, or to a Rack application. It can also generate paths and URLs, avoiding the need to hardcode strings in your views.
 
 ### Connecting URLs to Code