To work with Retrofit, you will require the following three classes:

• A model class, which is utilized as a JSON model
• Interfaces that characterize the conceivable HTTP activities
•  The Retrofit.Builder class, which utilizes the interface and the developer programming interface to permit characterizing the URL endpoint for HTTP activities.

Each function of an interface speaks to one conceivable programming interface call. It must have an HTTP annotation (GET, POST, DELETE, and so on) to determine the request type and the relative URL.