Localhost

A localhost is a website installed and then used on the same computer.

In [techie] talk   
  " A localhost is a Internet Protocol loopback device which can be used by 
    TCP/IP applications  to talk to themselves."

The default internal loop IP for the localhost is usually 127.0.0.1 . This IP is different from the IP that identifies the computer on the network.

Example. After installing one of Moodle's Complete install packages for Windows on a Windows machine, the user is instructed to open up a web browser and type "localhost" in the address bar.

A localhost webserver sometimes can be seen by other computers on the same network. For example, a teacher might have one computer in the classroom initially set up as a localhost with a Moodle on it. The 5 other computers students use as workstations can see that Moodle if they are on the same network. The students need to know the Moodle computer's network IP address and type that in their address bar of their browser. However, students will not be able to use it from home.