From Tapestries MUCK
Telnet is a Internet protocol that was designed to remote login to computers. It is also the name of a program that implements the protocol. More information can be found at Wikipedia:Telnet.
TinyMUCKs use the telnet protocol to talk to it's users. However, it's strongly recommended that you use one of many MUCK Clients.
Really. I can't stress how sad you will be trying to use the telnet program.