Update TODO.md

playground testing

Author: johncorderox

TODO.md

@@ -3,3 +3,23 @@
 1. Rails Serializers
 2. JWT
 3. Rack::Attack
+
+
+
+# Rails Serializers
+
+What are Serializers? Well Rails API's returns JSON data in full, so serializers allows us to cherry pick the exact data we want in a much organized fashion. Instead of getting every column from the returned data, we can grab which ever we allow to pass through.
+
+| Normal Model        | Serializer Model    | 
+| ------------- |:-------------:|
+| id, name, rating, director, score, actors_id, created_at, updated_at| id, name, rating|
+
+We are able to tell the Rails API what to fetch rather than the frontend; making it much more simple and faster to scaffold your next project.
+
+1. Installation
+
+Open your ```gemfile``` and add the serializer gem into your project 
+```ruby
+# Serializer
+gem 'active_model_serializers'
+```