Appletalk is a suite of protocols developed by Apple Computer for computer networking.
The implementation fairly rigorously followed the OSI model.
In its implementation based on serial transmission mechanisms Localtalk it was one of the first protocols to allow a number of computers to be networked together with other devices such as printers.
A later implementation Ethertalk operated over Ethernet.
It is now considered clunky and often called 'verbose'. It does not work well in a Wide area network environment (but it does work). Modern Apple computers use TCP-IP by default for networking.