One of the oldest protocols and at the same time most used is the FTP, or File Transfer Protocol, that appeared in the 70's, and that had various specification modification during the 80s'. The truth is that it is one of the best ways to transfer files between a client and a server of those currently available. Even though many programs integrate compatibility with this protocol, a good client like Cyberduck will always come in handy to make the most of it.
FTP client for Mac
This open source application is compatible with the SFTP protocol that adds a certain level of security to the data transfers, but it can also be used with FTP-SSL, SSH or WebDAH connection. The truth is that Cyberduck is one of the most complete FTP clients that exist for Mac OS X. It can save any connection or perform a quick connection, as well as being compatible with MobileMe iDisk, the Amazon S3 service and Rackspace Cloud Files without requiring any configuration at all.
A free FTP manager.
All the latter with a really brilliant interface that is fully integrated into Mac OS X. On the other hand, how it works is relatively different to that of other common FTP clients, because in Cyberduck we won't see our computer's folder, but it will easily allow us to drag and drop any file from the server to wherever we want.
Furthermore, this client is focused on web publishing, and due to this fact, it's compatible and integrates with several web editors, including SubEthaEdit, BBEdit, TextWrangler, Text-Edit Plus, TextMate, Smultron, JeditX, CSSEdit and PageSpinner.