Question:
What are .htaccess and .htpasswd files? And what can they do?

Answer:
.htaccess and .htpasswd files can be used to password protect directories on Unix hosted websites. They can prevent people from accessing a directory and all files in it, unless they enter a correct user name and password.

Some .htaccess tutorials are here:
http://hoohoo.ncsa.uiuc.edu/docs/tutorials/user.html
http://www.barmaton.nl/help/htaccess.html

A .htpasswd toolkit can be found here:
http://www.dansie.net/htpasswd_toolkit.zip