The TCP/ IP protocol suite includes a simple textual remote terminal protocols called TELNET that allow a user to log into a computer across an internet. TELNET establishes a TCP connection and then passes keystrokes from the internet user keyboard directly to the remote computer as if they had been typed on a keyboard attached to the remote machine. TELNET also carries textual output from the remote machine back to the user screen. The service is called transparent because it gives the appearance that the user keyboards and display attach directly to the remote machine.
TELNET offers three basic services. First it defines a network virtual terminal that provides a standard interface to remote systems. Client programs do not have to understand the details of all possible remote systems they are built to use the standard interface. Second TELNET include a mechanism that allows the client and server to negotiate options and it provides a set of standard option ( e ,g one of the option controls whether data passed across the connection uses the standard7 bit ASCII character set or an 8 bit character set). Finally TELNET treats both ends of eh connection symmetrically. In particular. TELNET does not force client input to come from a keyboard not does it force the client to display output on a screen. Thus TELNET allows an arbitrary program to become a client. Furthermore either end can negotiate options.