9 files changed, 35 insertions, 28 deletions
diff --git a/guides/source/active_record_validations.md b/guides/source/active_record_validations.md
index 7f88c13dc0..dd4d9f55fa 100644
--- a/guides/source/active_record_validations.md
+++ b/guides/source/active_record_validations.md
@@ -149,8 +149,10 @@ false` as an argument. This technique should be used with caution.
 
 ### `valid?` and `invalid?`
 
-To verify whether or not an object is valid, Rails uses the `valid?` method.
-You can also use this method on your own. `valid?` triggers your validations
+Before saving an ActiveRecord object, Rails runs your validations.
+If these validations produce any errors, Rails does not save the object.
+
+You can also run these validations on your own. `valid?` triggers your validations
 and returns true if no errors were found in the object, and false otherwise.
 As you saw above:
 
@@ -168,8 +170,9 @@ through the `errors.messages` instance method, which returns a collection of err
 By definition, an object is valid if this collection is empty after running
 validations.
 
-Note that an object instantiated with `new` will not report errors even if it's
-technically invalid, because validations are not run when using `new`.
+Note that an object instantiated with `new` will not report errors
+even if it's technically invalid, because validations are automatically run
+only when the object is saved, such as with the `create` or `save` methods.
 
 ```ruby
 class Person < ActiveRecord::Base
@@ -986,6 +989,10 @@ class method, passing in the symbols for the validation methods' names.
 You can pass more than one symbol for each class method and the respective
 validations will be run in the same order as they were registered.
 
+The `valid?` method will verify that the errors collection is empty,
+so your custom validation methods should add errors to it when you
+wish validation to fail:
+
 ```ruby
 class Invoice < ActiveRecord::Base
   validate :expiration_date_cannot_be_in_the_past,
@@ -1005,9 +1012,10 @@ class Invoice < ActiveRecord::Base
 end
 ```
 
-By default such validations will run every time you call `valid?`. It is also
-possible to control when to run these custom validations by giving an `:on`
-option to the `validate` method, with either: `:create` or `:update`.
+By default, such validations will run every time you call `valid?`
+or save the object. But it is also possible to control when to run these
+custom validations by giving an `:on` option to the `validate` method,
+with either: `:create` or `:update`.
 
 ```ruby
 class Invoice < ActiveRecord::Base
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 5a68f6c869..556b5ede3c 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -453,7 +453,7 @@ NOTE: Defined in `active_support/core_ext/object/instance_variables.rb`.
 
 #### `instance_variable_names`
 
-The method `instance_variable_names` returns an array.  Each name includes the "@" sign.
+The method `instance_variable_names` returns an array. Each name includes the "@" sign.
 
 ```ruby
 class C
@@ -2073,30 +2073,22 @@ Extensions to `BigDecimal`
 --------------------------
 ### `to_s`
 
-The method `to_s` is aliased to `to_formatted_s`. This provides a convenient way to display a BigDecimal value in floating-point notation:
+The method `to_s` provides a default specifier of "F". This means that a simple call to `to_s` will result in floating point representation instead of engineering notation:
 
 ```ruby
 BigDecimal.new(5.00, 6).to_s  # => "5.0"
 ```
 
-### `to_formatted_s`
-
-Te method `to_formatted_s` provides a default specifier of "F".  This means that a simple call to `to_formatted_s` or `to_s` will result in floating point representation instead of engineering notation:
-
-```ruby
-BigDecimal.new(5.00, 6).to_formatted_s  # => "5.0"
-```
-
 and that symbol specifiers are also supported:
 
 ```ruby
-BigDecimal.new(5.00, 6).to_formatted_s(:db)  # => "5.0"
+BigDecimal.new(5.00, 6).to_s(:db)  # => "5.0"
 ```
 
 Engineering notation is still supported:
 
 ```ruby
-BigDecimal.new(5.00, 6).to_formatted_s("e")  # => "0.5E1"
+BigDecimal.new(5.00, 6).to_s("e")  # => "0.5E1"
 ```
 
 Extensions to `Enumerable`
diff --git a/guides/source/active_support_instrumentation.md b/guides/source/active_support_instrumentation.md
index e5a560edd0..f495acbf68 100644
--- a/guides/source/active_support_instrumentation.md
+++ b/guides/source/active_support_instrumentation.md
@@ -232,6 +232,7 @@ Active Record
 | `:sql`           | SQL statement         |
 | `:name`          | Name of the operation |
 | `:connection_id` | `self.object_id`      |
+| `:binds`         | Bind parameters       |
 
 INFO. The adapters will add their own data as well.
 
diff --git a/guides/source/api_documentation_guidelines.md b/guides/source/api_documentation_guidelines.md
index 526bf768cc..73e62eb6d9 100644
--- a/guides/source/api_documentation_guidelines.md
+++ b/guides/source/api_documentation_guidelines.md
@@ -84,10 +84,11 @@ English
 
 Please use American English (*color*, *center*, *modularize*, etc). See [a list of American and British English spelling differences here](http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences).
 
-Comma
--------
+Oxford Comma
+------------
 
-Please use the Oxford comma (*red, white, and blue* style). See [the detail of Oxford comma](http://en.wikipedia.org/wiki/Serial_comma).
+Please use the [Oxford comma](http://en.wikipedia.org/wiki/Serial_comma)
+("red, white, and blue", instead of "red, white and blue").
 
 Example Code
 ------------
diff --git a/guides/source/asset_pipeline.md b/guides/source/asset_pipeline.md
index 7b8d2d3aef..41881abb62 100644
--- a/guides/source/asset_pipeline.md
+++ b/guides/source/asset_pipeline.md
@@ -662,7 +662,7 @@ generates something like this:
 rel="stylesheet" />
 ```
 
-Note: with the Asset Pipeline the :cache and :concat options aren't used
+NOTE: with the Asset Pipeline the `:cache` and `:concat` options aren't used
 anymore, delete these options from the `javascript_include_tag` and
 `stylesheet_link_tag`.
 
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index 87114c4ef0..e2125cae2e 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -304,13 +304,19 @@ All these configuration options are delegated to the `I18n` library.
   `:all` which always dumps all schemas regardless of the schema_search_path,
   or a string of comma separated schemas.
 
-* `config.active_record.belongs_to_required_by_default` is a boolean value and controls whether `belongs_to` association is required by default.
+* `config.active_record.belongs_to_required_by_default` is a boolean value and
+  controls whether a record fails validation if `belongs_to` association is not
+  present.
 
 * `config.active_record.warn_on_records_fetched_greater_than` allows setting a
   warning threshold for query result size. If the number of records returned
   by a query exceeds the threshold, a warning is logged. This can be used to
   identify queries which might be causing memory bloat.
 
+* `config.active_record.index_nested_attribute_errors` allows errors for nested
+  has_many relationships to be displayed with an index as well as the error.
+  Defaults to false.
+
 The MySQL adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns in a MySQL database to be booleans and is true by default.
diff --git a/guides/source/engines.md b/guides/source/engines.md
index 71844b7990..f961b799f1 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -670,7 +670,7 @@ pre-defined path which may be customizable.
 The engine contains migrations for the `blorgh_articles` and `blorgh_comments`
 table which need to be created in the application's database so that the
 engine's models can query them correctly. To copy these migrations into the
-application use this command:
+application run the following command from the `test/dummy` directory of your Rails engine:
 
 ```bash
 $ rake blorgh:install:migrations
diff --git a/guides/source/initialization.md b/guides/source/initialization.md
index 43083ebb86..ebe1cb206a 100644
--- a/guides/source/initialization.md
+++ b/guides/source/initialization.md
@@ -86,10 +86,9 @@ The `APP_PATH` constant will be used later in `rails/commands`. The `config/boot
 `config/boot.rb` contains:
 
 ```ruby
-# Set up gems listed in the Gemfile.
 ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../../Gemfile', __FILE__)
 
-require 'bundler/setup' if File.exist?(ENV['BUNDLE_GEMFILE'])
+require 'bundler/setup' # Set up gems listed in the Gemfile.
 ```
 
 In a standard Rails application, there's a `Gemfile` which declares all
diff --git a/guides/source/routing.md b/guides/source/routing.md
index 3175716a9c..245689932b 100644
--- a/guides/source/routing.md
+++ b/guides/source/routing.md
@@ -79,7 +79,7 @@ it asks the router to map it to a controller action. If the first matching route
 resources :photos
 ```
 
-Rails would dispatch that request to the `destroy` method on the `photos` controller with `{ id: '17' }` in `params`.
+Rails would dispatch that request to the `destroy` action on the `photos` controller with `{ id: '17' }` in `params`.
 
 ### CRUD, Verbs, and Actions