What is REST API?

REST API is an architectural style, not a standard, for building distributed systems. It is based on principles such as statelessness, client-server architecture, and the use of standard HTTP methods (GET, POST, PUT, DELETE, PATCH) for resource operations.

Key principles of REST:

• Stateless: The server does not store information about the client's state between requests. Each request contains all the necessary information for processing.
• Client-Server: Clear separation of client and server. Each can evolve independently.
• Cacheable: Responses can be marked as cacheable or non-cacheable, improving performance.
• Layered System: The client cannot tell whether it is connected directly to the server or through intermediate layers.
• Uniform Interface: Standardized ways of interacting with resources, including:
  • Resource identification (URI)
  • Manipulation of resources through representations
  • Self-descriptive messages
  • Hypermedia as the Engine of Application State (HATEOAS) - application state is managed through hypermedia links.

Example of using standard HTTP methods:

HTTP Method	Action on resource (e.g., /users)	Description
GET	/users or /users/{id}	Retrieve a list of users or a specific user.
POST	/users	Create a new user.
PUT	/users/{id}	Fully update user data by ID.
PATCH	/users/{id}	Partially update user data by ID.
DELETE	/users/{id}	Delete user by ID.

REST APIs are used for interaction between different systems and applications, such as between frontend and backend.