Telnet is a process (and a program) that allows your computer to connect or log on to a remote computer and use the other computer as if it were your own. Your computer becomes a "dumb" terminal.   Thus, when the telnet session is established, you must use the commands of the remote computer to get your computer to work.

When or why would you use telnet?  A lot of library catalogs are Telnet sites that will require you to use the Telnet tool to connect. Also, you can telnet to government agencies and universities. Some university students may also Telnet to check their email.