APIs are the backbone of modern web and mobile applications, allowing systems to communicate and exchange data. One of the most common styles of APIs is the RESTful API — short for Representational State Transfer.

In this article, we’ll break down the key concepts of RESTful APIs:

• What makes an API “RESTful”

• HTTP Methods and their meanings

• Status codes and what they tell us

• Structuring endpoints the right way

✅ What Is a RESTful API?

A RESTful API adheres to REST principles and uses standard HTTP methods to perform operations on resources, typically represented in JSON format.

Key characteristics:

• Stateless: Each request is independent.

• Uniform interface: Standardized way to access resources.

• Resource-based: Each object is treated as a resource with its own URI.

• Uses standard HTTP verbs: GET, POST, PUT, DELETE, etc.

HTTP Methods Explained

Each method has a specific role when interacting with a resource:

Example: Blog Post API

GET     /posts           → List all posts  
POST    /posts           → Create a new post  
GET     /posts/5         → Retrieve post with ID 5  
PUT     /posts/5         → Replace post 5  
PATCH   /posts/5         → Update post 5’s fields  
DELETE  /posts/5         → Delete post 5

HTTP Status Codes

Each API response comes with an HTTP status code that indicates the result of the request. These are grouped into categories:

Informational (100–199)

Rarely used in REST APIs.

Success (200–299)

Redirection (300–399)

Not commonly used in APIs.

Client Error (400–499)

Server Error (500–599)

Structuring REST Endpoints

REST endpoints should be clean, predictable, and resource-based.

1. Use Nouns, Not Verbs

Bad:

POST /createUser  
GET /getUser/1

Good:

POST /users  
GET /users/1

2. Plural Resource Names

Consistent naming helps with scalability.

✅ GET /posts
✅ POST /posts
✅ GET /posts/1

REST API Example: Bookstore

REST Design Tips

• ✅ Use consistent naming (/users, not /Users or /user)

• ✅ Nest resources only when necessary (/users/1/posts)

• ✅ Use HTTP status codes properly

• ✅ Avoid actions in URLs (/users/1/delete ❌)

• ✅ Keep URLs stateless (no session-based logic)

⚠️ Common Mistakes to Avoid

Final Thoughts

Understanding RESTful concepts like HTTP methods, status codes, and endpoints is crucial for building modern APIs. Whether you're building a backend with Django, Node.js, or Flask, following REST principles ensures that your API is intuitive, scalable, and easy to maintain.

RESTful APIs are not just about sending data — they're about clear communication between systems.