In computer networking, each connected device gets a unique label that identifies the device on the network. This label is known as a hostname. Localhost is the default hostname a computer uses to identify itself and its own internal network. It’s a respective term all computers apply to themselves. No matter what computer you are using, that computer always refers to itself as localhost. In the context of websites and web development, when saying localhost, one usually means local web development environment, when the copy of a website is hosted on the developer’s own machine.