REST API
A B C D E F G H I K L M N O P Q R S T U V W Z
Contents:

What Is a REST API?

A REST API (Representational State Transfer Application Programming Interface) is a standardized architectural approach for enabling communication between software systems over HTTP, using the same protocol that powers the World Wide Web. REST APIs allow applications to request, create, update, or delete data and functionality exposed by another system through a defined set of endpoints, each representing a specific resource, using standard HTTP methods to indicate the type of operation being performed.
REST APIs are the most widely adopted integration standard for web services and cloud platforms. They enable the interoperability between systems that makes modern digital ecosystems possible: mobile applications connecting to backend services, SaaS platforms exposing data to third-party integrations, and cloud services communicating with each other all commonly use REST APIs as the integration mechanism.

The Core Principles of REST Architecture

Statelessness

Each API request contains all the information the server needs to fulfill. The server does not retain session state between requests from the same client. This design makes REST APIs scalable and resilient because any server instance can handle any request without knowledge of prior interactions.

Resource-Based Design

REST APIs are organized around resources (the nouns of the API) rather than actions (the verbs). A customer is a resource accessible at a defined URL endpoint; the action performed on that resource (retrieve, create, update, delete) is communicated through the HTTP method used in the request.

Uniform Interface

REST APIs use a consistent, predictable set of HTTP methods: GET retrieves a resource; POST creates a new resource; PUT or PATCH updates an existing resource; DELETE removes a resource. This consistency allows developers to predict how an API behaves before reading its documentation.

REST API Response Formats and Status Codes

REST APIs typically return responses in JSON (JavaScript Object Notation) format, which is lightweight, human-readable, and universally supported across programming languages and platforms. HTTP status codes communicate the outcome of each request: 200 indicates success; 201 indicates a resource was created; 400 indicates a bad request from the client; 401 indicates authentication failure; 404 indicates the requested resource was not found; 500 indicates a server-side error.

REST API Security Considerations

Securing REST APIs requires authentication (verifying caller identity through API keys, OAuth tokens, or JWT), authorization (confirming the caller has permission to perform the requested operation), rate limiting (preventing abuse through excessive request volume), and encryption in transit through TLS. APIs that handle sensitive data require the same security rigor applied to any other system with access to that data.

Key Takeaways

  • REST APIs enable communication between software systems over HTTP using a standardized, resource-based architecture.
  • Core principles include statelessness, resource-based design, and a uniform interface using standard HTTP methods.
  • GET, POST, PUT/PATCH, and DELETE are the standard HTTP methods for retrieving, creating, updating, and deleting resources.
  • JSON is the standard response format; HTTP status codes communicate the outcome of each request.
  • REST API security requires authentication, authorization, rate limiting, and TLS encryption as foundational controls.
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