# What is a REST API?

> What is a REST API? Learn how RESTful APIs work, REST principles, common patterns, and how they connect mobile and web apps to backend services.

Canonical: https://app369.com/glossary/what-is-rest-api/

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Quick Answer

**A REST API (Representational State Transfer Application Programming Interface) is the most common way for apps to communicate with servers. It uses standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources identified by URLs.**

A **REST API** is the standard way mobile and web apps communicate with servers. REST stands for Representational State Transfer, an architectural style defined by Roy Fielding in 2000. It uses familiar HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources identified by URLs.

## How REST APIs Work

Every resource in a REST API has a URL. For example, a blog application might have these endpoints:

- `GET /api/posts`: Retrieve all blog posts
- `GET /api/posts/42`: Retrieve blog post #42
- `POST /api/posts`: Create a new blog post
- `PUT /api/posts/42`: Update blog post #42
- `DELETE /api/posts/42`: Delete blog post #42

The client sends a request, the server processes it, and returns a response (usually in JSON format) with an HTTP status code indicating success or failure.

## REST Principles

**Stateless.** Each request contains all the information the server needs to process it. The server does not store session state between requests.

**Resource-based.** Everything is a resource (user, post, order) with a unique URL. Actions on resources map to HTTP methods.

**Uniform interface.** All resources use the same consistent patterns for URLs, methods, and response formats. This predictability makes APIs easier to learn and use.

## REST vs GraphQL

REST is simpler, widely understood, and benefits from HTTP caching. [GraphQL](https://app369.com/glossary/what-is-graphql/) is more flexible, allowing clients to request exactly the data they need. Most applications work well with REST. GraphQL shines when you have multiple client types needing different data or complex data relationships.

## REST APIs at App369

At [App369](https://app369.com), REST APIs are the backbone of most applications we build. We design clean, well-documented APIs that are easy for frontend teams to consume and maintain. [Contact us](https://app369.com/contact/) to discuss your API architecture.

## **Related Terms **

[what is api](https://app369.com/glossary/what-is-api/) [what is graphql](https://app369.com/glossary/what-is-graphql/) [what is backend](https://app369.com/glossary/what-is-backend/)

## **Related Services **

[web apps](https://app369.com/service/web-apps/) [mobile apps](https://app369.com/service/mobile-apps/)

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