the Difference Between `localhost` and `127.0.0.1` IP Addresses

localhost is a hostname that refers to the current computer or device that you are using. It is commonly used to access web applications or server software that is running on the same machine. When you use the localhost hostname in a web browser or other networked application, it resolves to the IP address 127.0.0.1.

127.0.0.1 is a loopback IP address that is used to establish a connection to the same device that you are currently using. It is reserved for loopback purposes and is not used for any other purpose. When you use the IP address 127.0.0.1 in a web browser or other networked application, it establishes a connection to the same machine that you are using, just like the localhost hostname.

One of the key differences between localhost and 127.0.0.1 is how they are resolved. The localhost hostname is resolved by the operating system’s local Domain Name System (DNS) resolver. This means that when you use localhost in a web browser or other networked application, the operating system looks up the IP address associated with localhost in its DNS resolver and returns 127.0.0.1. On the other hand, 127.0.0.1 is a numeric IP address that is hard-coded into the network stack of the operating system, so it does not require any DNS resolution.

Another important difference is that localhost can be customized to resolve to a different IP address. This can be useful in situations where you need to test your application or website on a different machine or device. For example, if you have a web server running on your local machine and you want to test it on a different device on the same network, you can change the localhost hostname to resolve to your machine’s IP address on the network instead of 127.0.0.1.