Local Host refers to the computer in which a program runs. Local host is a host name given to address a particular computer connected to a network. In a nutshell, Local host is the address used by a web browser to check for a web server in user’s computer. So, when the localhost address is called from a web browser, it searches for that particular program and displays it on the browser. It is also called as Loopback address. When a program is run from multiple computers, it isn’t necessary to define localhost.