  * `.to_representation()` - Override this to support serialization, for read operations.
  * `.to_internal_value()` - Override this to support deserialization, for write operations.
  * `.create()` and `.update()` - Override either or both of these to support saving instances.
  
  Because this class provides the same interface as the `Serializer` class, you can use it with the existing generic class based views exactly as you would for a regular `Serializer` or `ModelSerializer`.
  
  The only difference you'll notice when doing so is the `BaseSerializer` classes will not generate HTML forms in the browsable API. This is because the data they return does not include all the field information that would allow each field to be rendered into a suitable HTML input.
  
  ##### Read-only `BaseSerializer` classes.
  
 
</s> remove A viewset is simply a type of class based view that allows you to group multiple views into a single common class.
 </s> add A viewset is simply a type of class-based view that allows you to group multiple views into a single common class. </s> remove Behavior for dealing with `OPTIONS` requests was previously built directly into the class based views. This has now been properly separated out into a Metadata API that allows the same pluggable style as other API policies in REST framework.
 </s> add Behavior for dealing with `OPTIONS` requests was previously built directly into the class-based views. This has now been properly separated out into a Metadata API that allows the same pluggable style as other API policies in REST framework.
Because this class provides the same interface as the `Serializer` class, you can use it with the existing generic class-based views exactly as you would for a regular `Serializer` or `ModelSerializer`.
  * `.to_representation()` - Override this to support serialization, for read operations.
  * `.to_internal_value()` - Override this to support deserialization, for write operations.
  * `.create()` and `.update()` - Override either or both of these to support saving instances.
  
Because this class provides the same interface as the `Serializer` class, you can use it with the existing generic class-based views exactly as you would for a regular `Serializer` or `ModelSerializer`.
  
  The only difference you'll notice when doing so is the `BaseSerializer` classes will not generate HTML forms in the browsable API. This is because the data they return does not include all the field information that would allow each field to be rendered into a suitable HTML input.
  
  ##### Read-only `BaseSerializer` classes.
  
keep keep keep keep replace keep keep keep keep keep
 Replace "class based views" occurrences with "class-based views" (#4251) 
docs/topics/3.0-announcement.md