I've been working with Django REST framework recently and going through the process of connecting it to React.js. There is a lot to digest throughout the whole process. Some points I'd like to note down are:
REST APIs:
APIs can basically be used to GET (or POST) JSON data. Many sites like Google Maps or Insta actually provide free to use APIs. The advantage of REST APIs over the basic back-end method of building apps and webpages is that because they use JSON the webpage and app can be viewed/used by all platforms from the get-go, rather than having to set up your website/app to work on Android, then later on iOS. Scaling is also made a lot easier through REST APIs.
Serializers:
A serializer class will convert our Models e.g the ones in models.py to JSON data.