What is localhost server name?

The localhost server name refers to the default name given to the local computer when it acts as a server. When setting up local web development or testing environments, the localhost name is used to access the local server from the browser. There are a few key things to know about localhost server names:

What is Localhost?

Localhost refers to the local computer itself. It is a hostname that the computer’s hosts file resolves to the IP address 127.0.0.1. This is a special IP address that always points back to the local computer. When you type “localhost” into a web browser, it will display a website hosted on the local development server rather than going out to the internet to fetch a page.

Some key facts about localhost:

• Localhost always resolves to 127.0.0.1
• 127.0.0.1 is known as the loopback address
• Loopback directs network traffic back to the local computer
• Localhost only exists on your local network
• Other computers cannot access your localhost

So in summary, localhost refers to your own machine and localhost websites or servers are only accessible from the same machine they are running on.

Why Use Localhost?

The main reasons to use localhost are for:

• Web development – test sites locally before deployment
• Accessing local databases and APIs
• Running services like local proxies or tunnels
• Testing connectivity to services running locally
• Isolating development from live infrastructure

Localhost provides an isolated environment for building and testing applications without impacting production servers. Developers can mimic live infrastructure and create realistic test scenarios without worrying about affecting real users.

Localhost Server Names

When running a local test server, there are a few common server names used with localhost:

• localhost – The default hostname pointing to 127.0.0.1.
• 127.0.0.1 – The IP address version of localhost.
• 0.0.0.0 – Used to listen on all available interfaces.
• dev.localhost – A common subdomain for development.
• test.localhost – A subdomain for testing purposes.
• local.projectname.com – Useful for mimicking live domains.

The actual name used doesn’t matter, as long as it resolves to 127.0.0.1. But these names help indicate the purpose of the local server. For example, a site for testing might use test.localhost as the hostname.

How Does Localhost Work?

Localhost relies on some key networking components to work:

• Loopback interface – A virtual network interface that points back to the local computer.
• Hosts file – Maps hostnames like localhost to 127.0.0.1.
• 127.0.0.1 – The standard loopback IP address.
• Local DNS – Resolves localhost names to 127.0.0.1.

Here is a more detailed explanation of the process:

1. A request is made to localhost in the browser, terminal, app, etc.
2. The operating system checks the hosts file and finds 127.0.0.1 mapped to localhost.
3. It resolves localhost to 127.0.0.1 immediately without having to query DNS servers.
4. The IP packet is sent to the loopback interface which directs it back to the local computer.
5. Any applications listening on 127.0.0.1 receive the request.

So while localhost appears to be a separate server, it is just a shortcut to access services running on the local machine via standard IP networking and loopback.

Common Uses of Localhost

Here are some of the most common uses of localhost:

Web Development

Web developers frequently use localhost to test changes on a private server before deploying to production. Frontend changes can be viewed immediately without needing to upload to a live server every time. Backend APIs can also be developed and tested locally.

Application Testing

Applications are often developed and tested against local test servers. Developers can spin up mocked services and databases to test connectivity and functionality during development.

Database Access

Database management tools will connect to localhost to manage local database instances. This allows administrating databases securely from the same machine instead of remotely.

Local Caching and Proxying

Services like Redis and Squid can run on localhost to provide local caching and proxying for reduced latency and improved security.

Tool and Utility Access

System admin tools and programming utilities are commonly hosted on localhost for local access. This includes things like phpMyAdmin, Python/Flask dev servers, etc.

Tunneling Traffic

Tunneling utilities like ngrok often run on localhost and tunnel external traffic to the local machine for remote debugging and testing.

Accessing Localhost from Other Devices

In some cases, you may want to access localhost from another device on the same network like a phone or tablet. There are a couple approaches to accomplish this:

Edit Hosts File

You can edit the hosts file on the external device to map localhost to the local IP address. For example:

127.0.0.1 localhost

192.168.1.100 localhost

Where 192.168.1.100 is the IP of your local dev machine. This effectively lets the external device access your dev environment through localhost.

Local Network Proxy

Another option is to setup a proxy on your local network that forwards localhost traffic from the external device to your dev machine. Tools like Charles Proxy or ngrok can accomplish this.

Expose App Directly

You can have your local dev server listen on your local IP/network directly instead of localhost. This exposes the ports directly rather than redirecting through localhost. Some framework dev servers like Flask provide this option.

In general, the hosts file edit is the easiest way to access localhost externally. Just be sure to remove the entry afterwards.

Potential Issues with Localhost

While localhost is very useful, there are some potential issues to be aware of:

• Accessing services externally – localhost is only accessible on the local machine by default.
• Port collisions – Different services trying to use the same port numbers.
• Cross-origin resource sharing errors – Localhost counts as a distinct origin.
• Differences from live infrastructure – Can’t fully mimic complex infrastructure.
• Obscures networking issues – Loopback interfaces can mask real world problems.
• Security – Localhost has less isolation and security than live servers.

Fortunately there are ways to overcome most of these. Port collisions can be avoided by properly configuring each local service. CORS proxies help deal with CORS issues in local development. And tools like Docker and Vagrant allow accurately mimicking complex infrastructure locally.

The main security concern is limiting access with firewall rules and keeping development machines isolated from production networks. Overall though, localhost remains an indispensable tool for web development and testing.

Conclusion

Localhost refers to the default name representing the local computer for development and testing purposes. It resolves to the loopback address 127.0.0.1 which directs traffic back to the local machine.

Common localhost server names like localhost and 127.0.0.1 provide an isolated local dev and testing environment. Web developers rely on localhost servers to efficiently test applications and websites before deployment. And a wide variety of tools utilize localhost for securely accessing local services.

Localhost serves as the gateway to development and testing environments running on the local machine. And while not a true separate server, to developers, localhost acts as the trusted local server powering their workflows.