What is api?

What is an API?

API stands for Application Programming Interface. It’s a mechanism that allows two software components to communicate with each other through a set of definitions and protocols.

Simple analogy: Think of an API like a waiter in a restaurant. You (the client) tell the waiter what you want, the waiter takes your order to the kitchen (the server), and then brings back your food (the response).

Real example: A weather app on your phone doesn’t generate weather data itself. Instead, it uses a meteorological institute’s API to request daily weather information, which the API then provides.

How Do APIs Work?

APIs act as intermediaries. Here’s the basic flow:

Client makes a request → “I need today’s weather for New York”
API processes the request → Connects to the server and retrieves the data
Server sends a response → Returns the weather information
Client receives and displays data → Shows it in your app

Types of APIs

REST API (Representational State Transfer)

Most popular and flexible type of API on the web today.

Client sends requests to the server as data (usually via HTTP)
Server processes the request and returns output data (typically JSON or XML)
Uses standard HTTP methods: GET, POST, PUT, DELETE
Example: GET https://api.weather.com/data/v1/current?city=NewYork

Why REST is popular: Simple, scalable, and works with any programming language.

SOAP API (Simple Object Access Protocol)

Uses XML for message exchange between client and server
More rigid and structured than REST
Less flexible and heavier—mostly used in legacy enterprise systems
Still found in banking and payment systems due to high security standards

RPC API (Remote Procedure Call)

Client executes a function or procedure on the server
Server runs the function and returns the result
Example types: XML-RPC, JSON-RPC, gRPC
Faster than REST for specific use cases but less flexible

WebSocket API

Enables bidirectional, real-time communication between client and server
Server can push messages to clients without waiting for requests
Uses JSON to transmit data
Perfect for: Chat applications, live notifications, gaming, stock trading platforms

Key difference from REST: Connection stays open, allowing continuous two-way communication instead of one request-response cycle.

REST vs WebSocket: When to Use Each

Feature	REST API	WebSocket API