In Telnet server and client communicate by passing data and commands in plaint text over the network. Though there are some security vulnerabilities associated with it.
Telnet client sends a request to the Telnet server to initiate a connection, once confirmed, the Telnet software logs in the user and allows the user to control the server remotely as if they were directly using the server's console.
The Telnet client initiates a connection request to the Telnet server. Once confirmed, the Telnet software logs in the user, enabling them to control the server remotely as if they were directly using the server's console.