Some remote hosts are set up to allow you to open an ftp connection to them even though you don't have an account on them. That's right, anyone can login and see what's available!
The convention is to use the username anonymous or ftp and then give your email address in place of a password.
Once you are connected to this type of host you can use the usual ftp commands and get any file(s) from amongst these that you are allowed access to. This type of host is used to hold public archives of documents, data and software.