What Are APIs? — How Apps Talk to Each Other

API stands for Application Programming Interface. That sounds complicated, but it is really simple: an API is a way for two programs to talk to each other. Think of a restaurant. You (the customer) do not go into the kitchen and cook your own food. Instead, you tell the waiter what you want, the waiter tells the kitchen, and the kitchen sends back your food. The waiter is like an API — a middleman that takes your request and delivers the response. When a weather app shows you the temperature, it is not measuring the weather itself. It sends a request to a weather API, which responds with the data. The app just displays it nicely.

Almost every app you use relies on APIs: - When you log in with Google on another website, that site uses Google's authentication API - When you see a map in an app, it is probably using Google Maps API - When a website shows a payment form, it uses Stripe's payment API - When an app shows you the weather, it uses a weather API - When a site shows YouTube videos embedded, it uses YouTube's API APIs let developers build on top of each other's work instead of reinventing the wheel. Why build a maps system from scratch when you can use one that already exists?

Most web APIs work with simple requests and responses: 1. Your app sends a REQUEST to a specific URL (called an endpoint) Example: GET https://api.weather.com/current?city=London 2. The server processes the request 3. The server sends back a RESPONSE with the data (usually in JSON format) Example: { 'temperature': 18, 'condition': 'cloudy' } The key methods (just like we learned in the internet lesson): - GET = 'Give me data' - POST = 'Save this new data' - PUT = 'Update this existing data' - DELETE = 'Remove this data'