What Is Localhost [Different Reasons to Use It & FAQ]

Like most computer users, you might not have paid too much attention to various computer jargon unless the situation called for some D-I-Y solution to fix a technical problem. So while you can get through much of your computing life without learning technical terms, it would be helpful to know at least the most common ones to build your computer literacy and vocabulary.

This What is a Localhost article addresses what a localhost is, how to use them, and other helpful information. 

What Is Localhost?

Casual computer users may find it daunting to delve into technical concepts, especially the self-proclaimed non-techy bunch. Simply put, localhost means ‘this computer.’ It’s the home machine that you’re using now. Some IT people also use the term ‘home computer’ or ‘local machine.’

In what context would you use localhost HTTPS? Suppose you’re a typical user, doing your usual business on your computer. In this case, you’re most likely not going to come across ‘localhost.’ But if you’re an IT person—or someone who tinkers around with networks and software applications—then ‘localhost’ is a staple in your vocabulary. 

To understand these concepts more clearly, you need to know that it’s all about communication. And when communicating, you always need a reference address. For instance, think of each computer as a building in a city—with each application installed as a respective resident. 

Buildings have different addresses. To locate a place, addresses are typically identified by street or building numbers. When a computer is connected to a network, it also uses an address to identify itself from all other computers in the network. But instead of using actual building addresses, computers use numerical codes called a hostname or IP address. (You may have come across numbers that look similar to 172.16.254.1.)

Continuing our building analogy, each time a resident wants to send a letter or package to someone from a different building, they need to indicate on the package the building address they’re sending the package to, as well as the sender’s address. In the same way, computers in a network use IP addresses to contact one another. Each application that wants to communicate with another application on another computer in the network must use an IP address to identify the source and the receiver correctly.

What Is a Loopback Address (127.0.0.1)?

What is 127.0.0.1, and how is it related to localhost? Using our building illustration, there might be occasions when residents from the same building would want to send a package to each other. Since they’re in the same building, each package would have the same building address. So residents could use a particular code/address agreed upon among themselves to send their package. This would be the IPV4 loopback, which indicates that a package will not leave the building but is destined only for fellow residents. 

If a resident, for example, from Unit 108 wishes to leave a package in the building’s lobby for Unit 202. In this case, the resident in Unit 202 will know precisely that the package in the lobby is for them (not for a resident of Unit 202 in another building)—as long as the code/address ‘202’ in their building is in the address. 

This code or address (127.0.0.1) is also known as the IP loopback address, which got its name because it ‘loops back’ requests and information to the same computer, also known as the localhost. 

How to Use Localhost? 

What is a localhost IP, and how do you use it? Some examples of the most common usages of localhost include:

Testing Applications

One of the most common uses for localhost is for testing applications. Today’s computer applications are designed to work over the internet, and these functions need to be tested. In addition, developers want to ensure that their programs will still run correctly once they have internet access.  

But some circumstances make it inconvenient if the tests are run over the actual internet—one of which includes speed. Around 100 milliseconds are consumed when information and requests are sent over the internet. This may not sound much, but for a developer who needs to test a lot of software and their functions repeatedly, faster is always better—hence the use of loopback IP addresses.

Running tests via the localhost means that you can simulate running applications over the internet without actually going through the internet. Instead, information is just looped back into your own machine, making running tests much faster. 

Speed Testing

Part of the job of a network administrator is to ensure that TCP/IP protocols—and all equipment in the network—are in order. Connection checks can be done by sending a ping request to the IPV4 loopback address. The process will be able to identify any errors and solutions to address them as well. 

Prevention of Browser Opening Websites

The internet is a great place to learn, explore, and do business. But it can also be a dangerous place. From phishing websites to inappropriate pages that you wouldn’t want to be associated with, there are some sites you want to stay away from.

While the previous examples of uses for localhosts and loopback addresses are geared more towards network engineers—or for those working on computer networking and other IT professionals—blocking websites is a localhost function that anyone will find a use for. For example, by setting up some configurations using the windows operating system (OS) host file, you can prevent your computer from opening certain websites. 

Conclusion

What is a localhost? It simply means the computer you are using. Localhost has a special IP address of 127.0.0.1, which is different from the IP address of your computer within the network. Purposes of the localhost’s function include application testing, speed testing, and blocking websites. Among these, blocking websites is the function that regular users mostly perform. 

(You might also want to check out our articles about the best website builders if you’re interested in all things IT.)