REST APIs (Representational State Transfer Application Programming Interfaces) are the foundation of modern application integration. They enable different applications, websites, and mobile apps to communicate securely over HTTP using standard methods such as GET, POST, PUT, PATCH, and DELETE. REST APIs are widely used in web development, cloud computing, mobile applications, and enterprise software because they are lightweight, scalable, and platform-independent.
A REST API is a way for different software applications to communicate with each other over HTTP using standardized principles.
For example, imagine an e-commerce application. The frontend may need customer information from a backend system. Instead of directly accessing the database, it can call an API such as:
GET /api/customers/1001
The server processes the request and may return customer information in JSON format.
Common HTTP methods include:
GET – Retrieve data
POST – Create new data
PUT – Replace or update data
PATCH – Partially update data
DELETE – Remove data
A typical REST API architecture looks like:
Frontend → REST API → Business Logic → Database
REST APIs are important because they separate the client application from the backend implementation. The frontend does not need to know how the database works; it only needs to understand the API contract.
Modern REST APIs also commonly use authentication and authorization mechanisms such as JWT, OAuth 2.0, or Microsoft Entra ID to protect resources.
For enterprise applications, good REST API design also requires attention to HTTP status codes, validation, pagination, versioning, security, error handling, logging, performance, and documentation.
In simple terms, a REST API acts as a controlled communication layer between different applications and systems, making it possible for modern software solutions to work together.