diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
index 6214802074..2cf39b68fb 100644
--- a/activemodel/lib/active_model/callbacks.rb
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -49,7 +49,7 @@ module ActiveModel
   #    puts 'block successfully called.'
   #  end
   #
-  # You can choose not to have all three callbacks by passing a hash to the
+  # You can choose to have only specific callbacks by passing a hash to the
   # +define_model_callbacks+ method.
   #
   #   define_model_callbacks :create, only: [:after, :before]
diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index ca5dac272f..c03e5fac79 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -118,7 +118,7 @@ module ActiveModel
       attribute_method_affix prefix: 'restore_', suffix: '!'
     end
 
-    # Returns +true+ if any attribute have unsaved changes, +false+ otherwise.
+    # Returns +true+ if any of the attributes have unsaved changes, +false+ otherwise.
     #
     #   person.changed? # => false
     #   person.name = 'bob'
@@ -166,7 +166,7 @@ module ActiveModel
       @changed_attributes ||= ActiveSupport::HashWithIndifferentAccess.new
     end
 
-    # Handle <tt>*_changed?</tt> for +method_missing+.
+    # Handles <tt>*_changed?</tt> for +method_missing+.
     def attribute_changed?(attr, options = {}) #:nodoc:
       result = changes_include?(attr)
       result &&= options[:to] == __send__(attr) if options.key?(:to)
@@ -174,7 +174,7 @@ module ActiveModel
       result
     end
 
-    # Handle <tt>*_was</tt> for +method_missing+.
+    # Handles <tt>*_was</tt> for +method_missing+.
     def attribute_was(attr) # :nodoc:
       attribute_changed?(attr) ? changed_attributes[attr] : __send__(attr)
     end
@@ -186,6 +186,7 @@ module ActiveModel
 
     private
 
+      # Returns +true+ if attr_name is changed, +false+ otherwise.
       def changes_include?(attr_name)
         attributes_changed_by_setter.include?(attr_name)
       end
@@ -197,18 +198,18 @@ module ActiveModel
         @changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
       end
 
-      # Clear all dirty data: current changes and previous changes.
+      # Clears all dirty data: current changes and previous changes.
       def clear_changes_information # :doc:
         @previously_changed = ActiveSupport::HashWithIndifferentAccess.new
         @changed_attributes = ActiveSupport::HashWithIndifferentAccess.new
       end
 
-      # Handle <tt>*_change</tt> for +method_missing+.
+      # Handles <tt>*_change</tt> for +method_missing+.
       def attribute_change(attr)
         [changed_attributes[attr], __send__(attr)] if attribute_changed?(attr)
       end
 
-      # Handle <tt>*_will_change!</tt> for +method_missing+.
+      # Handles <tt>*_will_change!</tt> for +method_missing+.
       def attribute_will_change!(attr)
         return if attribute_changed?(attr)
 
@@ -221,7 +222,7 @@ module ActiveModel
         set_attribute_was(attr, value)
       end
 
-      # Handle <tt>restore_*!</tt> for +method_missing+.
+      # Handles <tt>restore_*!</tt> for +method_missing+.
       def restore_attribute!(attr)
         if attribute_changed?(attr)
           __send__("#{attr}=", changed_attributes[attr])
@@ -230,7 +231,7 @@ module ActiveModel
       end
 
       # This is necessary because `changed_attributes` might be overridden in
-      # other implemntations (e.g. in `ActiveRecord`)
+      # other implementations (e.g. in `ActiveRecord`)
       alias_method :attributes_changed_by_setter, :changed_attributes # :nodoc:
 
       # Force an attribute to have a particular "before" value
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 5a3b4f0c40..260ef71e64 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1438,7 +1438,7 @@ module ActiveRecord
       # when you access the associated object.
       #
       # Scope examples:
-      #   belongs_to :user, -> { where(id: 2) }
+      #   belongs_to :firm, -> { where(id: 2) }
       #   belongs_to :user, -> { joins(:friends) }
       #   belongs_to :level, ->(level) { where("game_level > ?", level.current) }
       #
@@ -1516,9 +1516,9 @@ module ActiveRecord
       #   belongs_to :attachable, polymorphic: true
       #   belongs_to :project, readonly: true
       #   belongs_to :post, counter_cache: true
-      #   belongs_to :company, touch: true
+      #   belongs_to :comment, touch: true
       #   belongs_to :company, touch: :employees_last_updated_at
-      #   belongs_to :company, required: true
+      #   belongs_to :user, required: true
       def belongs_to(name, scope = nil, options = {})
         reflection = Builder::BelongsTo.build(self, name, scope, options)
         Reflection.add_reflection self, name, reflection
diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 51cf468d2b..f32bb8a0cc 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -741,8 +741,8 @@ module ActiveSupport
       #
       # * <tt>:skip_after_callbacks_if_terminated</tt> - Determines if after
       #   callbacks should be terminated by the <tt>:terminator</tt> option. By
-      #   default after callbacks executed no matter if callback chain was
-      #   terminated or not. Option makes sense only when <tt>:terminator</tt>
+      #   default after callbacks are executed no matter if callback chain was
+      #   terminated or not. This option makes sense only when <tt>:terminator</tt>
       #   option is specified.
       #
       # * <tt>:scope</tt> - Indicates which methods should be executed when an
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index 8633cc4f10..3484627a78 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -171,7 +171,7 @@ class CreateCustomers < ActiveRecord::Migration
     end
 
     create_table :orders do |t|
-      t.belongs_to :customer, index:true
+      t.belongs_to :customer, index: true
       t.datetime :order_date
       t.timestamps null: false
     end
@@ -691,7 +691,7 @@ c.first_name = 'Manny'
 c.first_name == o.customer.first_name # => false
 ```
 
-This happens because c and o.customer are two different in-memory representations of the same data, and neither one is automatically refreshed from changes to the other. Active Record provides the `:inverse_of` option so that you can inform it of these relations:
+This happens because `c` and `o.customer` are two different in-memory representations of the same data, and neither one is automatically refreshed from changes to the other. Active Record provides the `:inverse_of` option so that you can inform it of these relations:
 
 ```ruby
 class Customer < ActiveRecord::Base
@@ -726,10 +726,10 @@ Most associations with standard names will be supported. However, associations
 that contain the following options will not have their inverses set
 automatically:
 
-* :conditions
-* :through
-* :polymorphic
-* :foreign_key
+* `:conditions`
+* `:through`
+* `:polymorphic`
+* `:foreign_key`
 
 Detailed Association Reference
 ------------------------------