What Is an API?

In today’s digital world, apps and websites often talk to each other. This communication happens through something called an API — short for Application Programming Interface.

What Does an API Do?

An API is like a messenger.

• It sends your request to another system.

• It brings back the answer so your app can show it.

Imagine you open a food delivery app and want to see pizza shops nearby.

• Your app sends a request through an API to a server.

• The server sends back a list of shops.

• The app shows it to you.

How Does an API Work?

You (the user or app) send a request → “Give me data!”
The API takes the request → Goes to the server.
The server processes it → Finds the data.
The API returns the result → App displays it.

Common API Terms

Request

The data your app sends to the API

Response

The data the API sends back

Endpoint

The specific URL where the API listens

JSON	A common format for API data (looks like { "name": "Nepal" })

Why do we need the API

Imagine you’re building a food delivery app.

• You want to show the user’s location on a map.

• You want to find nearby pizza shops.

• You want to draw the delivery route.

Could you build your own map system?
That would take years, cost millions, and need constant updates.

Instead, you use Google Maps API

• Your app asks Google Maps: “Where is this address?”

• Google Maps API responds with the location, shops, route, etc.

• Your app shows the map, markers, and route — easy!

This is one example of API call:

GET https://api.weather.com/v3/weather/forecast?location=Kathmandu

This is how it’s response can look which we use as how we want to use in our case:

{
  "location": "Kathmandu",
  "forecasts": [
    {
      "day": "Monday",
      "high_temp_c": 28,
      "low_temp_c": 18,
      "description": "Partly cloudy"
    }
  ]
}

Moreover, An API is secured by using API keys so only authorized apps can access it. To prevent overuse, throttling (rate limiting) controls how many requests are allowed in a time period, like 100 requests per minute. Common throttling methods include fixed window and token bucket.

This keeps the API safe, reliable, and fair.