4.14.3 ‘Terminal-type string’

Most servers you might connect to with PuTTY are designed to be connected to from lots of different types of terminal. In order to send the right control sequences to each one, the server will need to know what type of terminal it is dealing with. Therefore, each of the SSH, Telnet and Rlogin protocols allow a text string to be sent down the connection describing the terminal. On a Unix server, this selects an entry from the termcap or terminfo database that tells applications what control sequences to send to the terminal, and what character sequences to expect the keyboard to generate.

PuTTY attempts to emulate the Unix xterm program, and by default it reflects this by sending xterm as a terminal-type string. If you find this is not doing what you want - perhaps the remote system reports ‘Unknown terminal type’ - you could try setting this to something different, such as vt220.

If you're not sure whether a problem is due to the terminal type setting or not, you probably need to consult the manual for your application or your server.