FTP is an application protocol that allows the transfer of files across a network. It's a fairly complex protocol which allows login to a remote file system, the navigation of file systems at both local and remote ends of the link, and the transfer of data in both directions (that is upload and download). FTP uses two connections: a control channel (port 21) that is used for login, navigation and for submitting file transfer requests, and a data separate channel (port 20) that is used for individual file transfers. FTP requires user state to be maintained on both the client and server so it is an example of a stateful protocol.

Modern user agents for FTP typically hide the complexity of FTP by creating a file explorer-like view of the local and remote file systems and allowing drag and drop manipulation of files.

Like Telnet, user credentials and passwords are sent plain text over the control channel, and so many ISPs require the use of a secure FTP client for file transfer.

Glossary : A | B | C | D | E | F | G | H | I | J | K | L | M | N | P | Q | R | S | T | U | V | W | X | Y | Z