What Happens During an API Call?

Back to API Design
Arjit Sharma
01 Min

So you understand what an API is, you understand how internet works !

But how do API works? What does your app actually do when it sends a request to an API like Google Maps or Zomato?

Step 1: A User Triggers an Action

Imagine a user taps “Track My Order”.

This tells the app “Go fetch the latest order status from the server”.

Step 2: The App Makes an HTTP Request

GET https://api.foodapp.com/v1/orders/123

Step 3: Networking Stack Does Its Thing

The device starts routing the request. Three key things happen:

  • DNS (Domain Name System) - Looks up api.foodapp.com and finds its IP, like 192.168.2.10.
  • IP (Internet Protocol) - ****Handles where the request should go (like the address on a letter).
  • TCP (Transmission Control Protocol) - ****Breaks the request into packets, ensures reliable delivery.

Step 4: Server Receives and Processes the Request

The server gets the request, looks up data from a database or other useful things and assembles a response.

The server sends a response like:

{
  "orderId": "123",
  "status": "On the way"
}

Step 5: The Client Gets a Response

The response returns over the same TCP/HTTP path. If all goes well we get a 200 OK . The app then parses the JSON and updates the UI.

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