`What is PuTTY?' gets asked _just_ frequently enough to have finally

annoyed me.

[originally from svn r3749]

doc/faq.but

@@ -1,10 +1,30 @@
-\versionid $Id: faq.but,v 1.51 2003/11/19 19:09:07 jacob Exp $
+\versionid $Id: faq.but,v 1.52 2004/01/21 17:11:55 simon Exp $
 
 \A{faq} PuTTY FAQ
 
 This FAQ is published on the PuTTY web site, and also provided as an
 appendix in the manual.
 
+\H{faq-intro} Introduction
+
+\S{faq-what} What is PuTTY?
+
+PuTTY is a client program for the SSH, Telnet and Rlogin network
+protocols.
+
+These protocols are all used to run a remote session on a computer,
+over a network. PuTTY implements the client end of that session: the
+end at which the session is displayed, rather than the end at which
+it runs.
+
+In really simple terms: you run PuTTY on a Windows machine, and tell
+it to connect to (for example) a Unix machine. PuTTY opens a window.
+Then, anything you type into that window is sent straight to the
+Unix machine, and everything the Unix machine sends back is
+displayed in the window. So you can work on the Unix machine as if
+you were sitting at its console, while actually sitting somewhere
+else.
+
 \H{faq-support} Features supported in PuTTY
 
 In general, if you want to know if PuTTY supports a particular