What is REST API?

REST API (Representational State Transfer Application Programming Interface) is an architectural style and set of guidelines for designing networked applications. It is widely used for building web services that can be consumed by client applications over the internet.

Here are some key characteristics and principles of REST APIs:

1. Statelessness: REST APIs are stateless, meaning that each request from a client to a server contains all the necessary information to process that request. The server does not store any client-specific information between requests. This design principle allows for scalability and simplifies the design and implementation of the server.

2. Resource-Based: REST APIs model the application as a set of resources that are identified by unique URLs (Uniform Resource Locators). Resources represent entities such as users, products, or articles. Each resource is typically associated with a unique URI, and clients interact with these resources by making HTTP requests to their corresponding URLs.

3. CRUD Operations: REST APIs provide a standardized set of methods to perform CRUD operations (Create, Read, Update, Delete) on resources. These methods align with the HTTP protocol's methods: GET (read), POST (create), PUT/PATCH (update), and DELETE (delete). By utilizing these methods, clients can perform various actions on the resources.

4. Stateless Operations: REST APIs treat each request as an independent operation, and the server does not maintain any client-specific state between requests. Clients include any necessary information in the request, such as authentication credentials or data payloads, to allow the server to process the request successfully.

5. Representation and Media Types: REST APIs use various media types to represent the resources being transferred. The most common media type is JSON (JavaScript Object Notation), but other formats like XML or even plain text can be used. The server specifies the media type in the response headers, and clients can request a specific media type through the "Accept" header.

6. Hypermedia as the Engine of Application State (HATEOAS): HATEOAS is a principle that suggests including hyperlinks in API responses to guide clients through the application's available actions and transitions. The API provides links to related resources or actions, allowing clients to navigate the API dynamically without prior knowledge.

REST APIs are widely adopted due to their simplicity, scalability, and compatibility with the HTTP protocol. They provide a standardized approach to building web services that can be easily consumed by various client applications, such as web browsers, mobile apps, or other backend systems. By adhering to the principles of REST, developers can create APIs that are well-structured, reliable, and interoperable.