APIs are like waiters in a restaurant. 🍜 The client (frontend/mobile app) gives a request, the server processes it, and the API delivers the response back.

In web development, REST APIs are one of the most common ways for apps to communicate.

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What is a REST API?

REST stands for Representational State Transfer.

A REST API follows a set of rules to manage and access resources using HTTP methods.

A resource can be anything:

• users

• products

• posts

• comments

Example:

/users

This represents a collection of users.

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HTTP Methods in REST

REST APIs mainly use four HTTP methods for CRUD operations.

Operation	HTTP Method	Example Route
Read	GET	/users
Create	POST	/users
Update	PUT	/users/1
Delete	DELETE	/users/1

Tiny naming mistake people make:

/getUsers
/createUser

This is not clean REST design because the HTTP method already tells the action. Your route should focus on the resource.

Correct way:

GET /users
POST /users

Your routes should look clean, not like a folder made by a sleep-deprived raccoon at 3AM.

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REST Request-Response Flow

1. Client sends request

2. Server receives request

3. Express handles route

4. Database logic runs

5. Response is returned

Example:

app.get('/users', (req, res) => {
  res.send('All users fetched');
});

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CRUD Example Using Express.js

const express = require('express');
const app = express();

app.use(express.json());

// GET users
app.get('/users', (req, res) => {
  res.status(200).json({ message: 'Users fetched' });
});

// POST user
app.post('/users', (req, res) => {
  res.status(201).json({ message: 'User created' });
});

// PUT user
app.put('/users/:id', (req, res) => {
  res.status(200).json({ message: 'User updated' });
});

// DELETE user
app.delete('/users/:id', (req, res) => {
  res.status(200).json({ message: 'User deleted' });
});

app.listen(3000, () => {
  console.log('Server running on port 3000');
});

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Status Codes Basics

Status codes tell the client what happened.

Status Code	Meaning
200	Success
201	Resource created
400	Bad request
404	Resource not found
500	Server error

Example:

res.status(404).json({ message: 'User not found' });

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Why REST APIs Matter

REST APIs make communication between frontend and backend structured and predictable.

Without proper API design, projects become chaos very quickly:

• confusing routes

• inconsistent responses

• impossible debugging

• future-you crying in production

Clean REST design keeps projects scalable and easier to maintain.

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Conclusion

REST APIs are the backbone of modern web applications. By following REST principles, using proper HTTP methods, and keeping routes resource-based, developers can build scalable and clean backend systems using Express.js.

Start simple:

/users
/products
/posts

Design around resources, not actions. That single habit already puts you ahead of many beginner backend developers.