This article is from the sci.fractals FAQ, by Michael C. Taylor and Jean-Pierre Louvet with numerous contributions by others.
Anonymous ftp is a method of making files available to anyone
on the Internet. In brief, if you are on a system with ftp (e.g.
Unix), you type "ftp fractal.mta.ca", or whatever system you wish to
access. You are prompted for your name and you reply "anonymous". You
are prompted for your password and you reply with your email address.
You then use "ls" to list the files, "cd" to change directories, "get"
to get files, an "quit" to exit. For example, you could say "cd /pub",
"ls", "get README", and "quit"; this would get you the file "README".
See the man page ftp(1) or ask someone at your site for more
In this FAQ, anonymous ftp addresses are given in the URL form
ftp://name.of.machine/pub/path [184.108.40.206]. The first part is the
protocol, FTP, rather than say "gopher", the second part
"name.of.machine" is the machine you must ftp to. If your machine
cannot determine the host from the name, you can try the numeric
Internet address: "ftp 220.127.116.11". The part after the name:
"/pub/path" is the file or directory to access once you are connected
to the remote machine.