TELNET is TErminal NETwork. Telnet is both a TCP/IP application & a protocol for connecting a local computer with a remote computer. It is a program which allows an Internet host computer to become a terminal of another host on the Internet. It is the Internet remote login service. Telnet protocol denotes exactly how a remote login interacts. The standard denote how to client contacts the server & how the server encodes output for transmission to the client. To employ the Telnet service, one has to invoke the local application program and denote a remote machine. The local program becomes a client that forms a connection to a server on the remote computer. The client passes mouse and keystrokes movements to the remote machine & displays output from the remote machine on the user's display screen. Telnet offer direct access to various services on Internet. Some services are obtainable on your host, however Telnet is especially useful while these services are not obtainable on your host. For instance, if you desire to use graphical interfaces designed through other users then Telnet, lets you to access their hosts and employ their new interfaces. Likewise, whenever someone creates a useful service on his host, Telnet lets you to access this valuable information resource. This tool is useful especially for accessing public services like library card catalogues, the kind of databases obtainable on the machine etc. You can also log in any catalogue service of library and employ it.