The Apple Filing Protocol (AFP), formerly AppleTalk Filing Protocol, is a proprietary network protocol, and part of the Apple File Service (AFS), that offers file services for macOS and the classic Mac OS. In macOS, AFP is one of several file services supported, with others including Server Message Block (SMB), Network File System (NFS), File Transfer Protocol (FTP), and WebDAV. AFP currently supports Unicode file names, POSIX and access control list permissions, resource forks, named extended attributes, and advanced file locking. In Mac OS 9 and earlier, AFP was the primary protocol for file services.
AFP versions 3.0 and greater rely exclusively on TCP/IP (port 548 or 427) for establishing communication, supporting AppleTalk only as a service discovery protocol. The AFP 2.x family supports both TCP/IP (using Data Stream Interface) and AppleTalk for communication and service discovery. Many third-party AFP implementations use AFP 2.x, thereby supporting AppleTalk as a connection method. Still earlier versions rely exclusively on AppleTalk. For this reason, some older literature refers to AFP as “AppleTalk Filing Protocol”. Other literature may refer to AFP as “AppleShare”, the name of the Mac OS 9 (and earlier) AFP client.