Telnet is a program or protocol that helps operate a distant server by connecting to another host using its Internet address, similar to PuTTY. The telnet protocol works by sending data typed on a real keyboard to a virtual keyboard, which then displays it on the user's computer screen through a virtual printer. Common telnet commands include using "telnet" followed by a host address to log in to a remote system, where the user would then enter their login credentials before having access to work on the remote host.