Localhost: What it is and How it works?

Posted by Joseph C. Speller on December 21st, 2020

Although localhost is sometimes used as synonymous with package programs such as WAMP, XAMPP, or EasyPHP, this is also an incorrect definition. These programs broadcast using localhost as well as with other IP addresses defined on the computer.

The term Localhost refers to the computer on which a program is running. It is a loopback device that is assigned IP Address in IPv4 (::1 for IPv6) and used to enable the computer to access it over TCP/IP.

Being able to communicate with the current machine as if it were communicating with a remote machine is useful for testing purposes, as well as for using features located on the current machine, but which are expected to be remote.

After briefly explaining what is localhost, what it means, I am going to provide detailed information and working logic that will clarify the definition.

Let’s talk about IP addresses

The IP (Internet Protocol) address is generally an address that indicates the place where a certain piece of equipment is located, which are usually computers.

In private networks, each computer has an IP address that shows the right way for the information to reach it. On the internet, it happens the same way. However, there are different standards and address ranges for each type.

When we type an address in the browser bar, the DNS server transforms the address you typed (example: www.Temok.com) for an IP number like this, it is possible to access the server where the site is hosted.

There are special classes of IP addressing and one of them is LOCALHOST which is very simple. When you have a server running on a machine like Apache if you type localhost the browser will redirect you to the server’s root folder. That is, LOCALHOST means the computer itself where a server is running and is often used for internal communication on a network. The localhost simulates the interaction with a remote machine, but being itself, so it can be used for tests on the network as well.

How does Localhost Work?

In the communication of two computers, data packets are sent and received within the framework of TCP / IP protocols. These packages contain the IP addresses of the receiver and the sender as well as the main information.

Computers look at the addresses in the packet to see which packets belong to them on the network. They respond by taking their own packages.

This does not cause a problem in communication between computers with different IP addresses on the same or different networks.

For example, a computer with an IP address of can easily communicate with a computer with an IP address of on the same network using TCP / IP protocols. They can easily distinguish which packets belong to the network card and respond.

However, for the hardware and software in a computer to communicate securely with a hardware or software within the same computer, an address different from the IP address on the network is required. To meet this requirement, the address block has been allocated and defined as localhost.

A virtual network card called a loopback device has been created to control communication over the localhost block created to enable the computer to access itself over TCP / IP.

Thanks to the virtual network card, outgoing data is directed to the computer itself via the address Thus, it is ensured that the data packets sent are returned to the computer itself without leaving the network where it is available so that the computer can communicate safely within itself as you can view in the diagram given below:

How does Localhost Work?

For example: Suppose you have installed WAMP Server on your computer to develop your website designs. With the Apache webserver included in the WAMP Server package, your web pages start to be published over the localhost: 80 port by default.

When you type localhost into your browser, you can view your web pages you designed. Here, for your web browser and the Apache server, localhost is your computer. Your request via the browser is answered by Apache on your computer before it reaches the modem.

Localhost IP Address

Localhost is used to access network services running on the host through a loopback network interface. Using the loopback interface bypasses the local network interface hardware. The local loopback mechanism can be used to run network services on a host without requiring a physical network interface or making the service accessible on the network to which the computer is connected. For example, you can access a locally installed website from a web browser via the URL http://localhost and display the home page.

The IPv4 network standard reserves the entire address block for loopback purposes. This means that all packets sent to one of those addresses ( will be looped back. This address does not change and is valid and the same for all computers. It enables communication between computer hardware. Address is a standard address commonly used for IPv4 loopback traffic. The rest are practically never used. The IPv6 standard only assigns a single address (:: 1) to loopback.

So it’s basically the localhost address used for testing software/applications. These are services provided internally by the operating system. You can ping the localhost address without a working network interface card “NIC”. Easy to test. Now disable the NIC then try pinging “127.x.x.x”.

0 = this. Address 0 is interpreted to mean “this” as in “this network”. For example, the address could be interpreted to mean host 37 on this network. All hosts’ addresses are interpreted to mean “all” as in “all hosts”. For example, the address could be interpreted as meaning 128.9 for all hosts on the network. Class A network number 127 is assigned a “loopback” function. This means that data packets sent to network 127 address in higher-level protocols must be looped back inside the host. Data packets “sent” to network 127 address should not appear on any network.

Final Words

Those who want to set up a WordPress website, those who deal with PHP, HTML, JavaScript coding, do their trials on localhost before they get hosting, that is, before opening the internet environment. You can start working after installing programs such as Wamp, XAMPP on the computer. By typing localhost or in your browser, you can access the pages and see how they will appear on the internet.

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Joseph C. Speller

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Joseph C. Speller
Joined: December 21st, 2020
Articles Posted: 10

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