Fullstack > Architecture > 🌐 REST APIs

Welcome to the world of web development!

A REST API (Representational State Transfer Application Programming Interface) is a way for different software programs or systems to communicate with each other over the internet, much like how humans use languages to communicate. Imagine you’re at a restaurant: you (the client) give your order (a request) to the waiter (the API), and the waiter passes your order to the kitchen (the server). The kitchen prepares your food (processes the request), and the waiter brings it back to you (the response). Just like how a menu lists available food options, the API lists different commands or actions that can be requested from the server, and the server responds with the information or data you asked for. REST APIs are used everywhere – from checking weather forecasts to sending messages on social media.

🧑‍💻 REST - Representational State Transfer

REST is an architectural style used for designing networked applications.

📦 REST API Characteristics

📏 REST API Standards

Standard Description
Stateless No session info stored on the server. Each request is independent.
Uniform Interface Consistent structure: URIs, methods, and formats.
Cacheable Responses can be cached to improve performance.
Layered System Client doesn’t know if it’s talking to the real server or a proxy.
Code on Demand (Optional) Servers can send executable code to clients (e.g., JavaScript).

🧾 HTTP Methods

Method Use Case
GET 🔍 Retrieve data from the server.
POST ➕ Create a new resource.
PUT 🔁 Update an existing resource (replace).
PATCH 🩹 Partially update a resource.
DELETE ❌ Remove a resource.

📤 HTTP Request Structure

GET /api/users HTTP/1.1
Host: example.com
Authorization: Bearer <token>
Content-Type: application/json

Components:

Part Description
Request Line Method + URL + HTTP Version
Headers Key-Value pairs for metadata (Auth, Content-Type, etc.)
Body Payload for POST/PUT/PATCH requests

📥 HTTP Response Structure

HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": 1,
  "name": "Alice"
}

Components:

Part Description
Status Line HTTP version + Status code + Status message
Headers Metadata (Content-Type, Caching, etc.)
Body Actual response data (typically JSON)

🧠 HTTP Headers (Common Ones)

Header Purpose
Authorization For authentication tokens
Content-Type Indicates format of request/response body
Accept Client’s preferred response format
Cache-Control Caching directives
User-Agent Info about the client making the request

📡 HTTP Response Codes

Code Meaning Description
200 OK ✅ Success Request was successful
201 Created 🆕 Resource created successfully  
204 No Content ✅ Success with no body  
400 Bad Request ⚠️ Client error (invalid input)  
401 Unauthorized 🔐 Missing or invalid auth  
403 Forbidden 🚫 Authenticated but no permission  
404 Not Found ❓ Resource not found  
500 Internal Server Error 💥 Something broke on the server  

🎯 Summary