Telnet: A text-based internet protocol, much older than http <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
Even windows has a telnet client nowadays (just try to open a command prompt and type "telnet") but what would you expect: that windows-telnet is just a crappy sh**. So there are programmers who do good work, and so the program "PuTTY" was developed.
http://www.chiark.greenend.org.uk/~sgtatham/putty/ 
