Written by Sümeyye Sever (notes I took while creating web development projects)
localhost is a hostname that refers to the local computer (your own device). It’s a way for software and servers running on your computer to communicate with each other using the network stack, even though the communication doesn’t leave your computer.
When developing or testing applications, you often use localhost to simulate how the application behaves without needing to host it on an external server.
How internet browser and my server can communicate locally?
- Server Side (Code Editor):
- You run a server in Node.js (or any other framework)
- The server binds to a port (e.g. 3000) on your computer.
- Client Side (Internet Browser):
- You use browser to send a request to
http://localhost:3000.
- Browser looks for a server running at
127.0.0.1 (localhost) on port 3000.
- Network Stack:
- The communication happens through your computer’s TCP/IP stack, just like any other internet communication. The difference is that the traffic doesn’t leave your computer.
- Request and Response:
- Browser sends the request → Your server processes it → Chrome receives the response.
Why Use localhost in Development?
- No Internet Needed: You don’t need an internet connection to test your application.
- Isolated Environment: You can test your app privately without exposing it to the public.
- Faster Iteration: Changes to your code can be quickly tested locally without deploying to a live server.