What is an API and How Does it Work?

What is an API?

An API (Application Programming Interface) lets two software systems talk to each other. It defines rules for requesting and exchanging data — like a waiter taking your order to the kitchen and bringing food back.

A Real Example

// Your app asks a weather API
GET https://api.weather.com/city/london

// The API responds with data
{ "city": "London", "temp": 15, "condition": "cloudy" }

How a Web API Works

1. Client sends an HTTP request to an endpoint.
2. Server processes it (maybe queries a database).
3. Server returns a response (usually JSON).

HTTP Methods

Method	Action
GET	Read data
POST	Create data
PUT	Update data
DELETE	Remove data

FAQs

What is REST?

A popular style of designing APIs using HTTP methods and URLs. More in our API Development guides.

Why use APIs?

To reuse functionality (payments, maps, auth) instead of building everything yourself.