This is an FTP that has left on anonymous access. Many are owned by large companies, so they have a lot of bandwidth. This makes it possible for one person to send files there and many people can download them at once =) These are found by scanning ranges of ips (see the FTP tutorial). Just remember, like the name says, these are public. Just because you upload something there or make directories with your name does not make it 'your pub'. At the same time, realize that if you come across a pub with another person/groups stuff on it that it may be in use to build other pubs from - so don't ruin it for many people by deleting stuff you find there. For more on this, go read some posts on our Bulletin Board.