It is primarily known as the socket used by Pentium M and Celeron M mobile processors normally found in laptops, however the socket has also been used with Tualatin-M Mobile Celeron and Pentium III processors years before it.

Pentium M processors in PGA package have 479 pins that plug into this zero insertion force socket.

There exist multiple electrically incompatible, but mechanically compatible processor families that are available in PGA packages using Socket 479 or variants thereof:[1] Each of these above-mentioned processor families have CPU packages that are mechanically similar yet are not electrically compatible with each other, and therefore accidentally inserting them into the wrong socket configurations will not work or may result in damage to the processor and/or the motherboard.

[5][6] Perhaps adding yet more confusion, some of the PGA-based CPUs above are also available in a BGA (or more precisely, μBGA or even μFCBGA) package which has all of the 479 contacts (balls) populated.

[7] It should be however pointed out that these designations denote rather the CPU package itself and not the socket, which the BGA variants do not use at all (they are intended to be directly soldered to the mainboard, e.g. in an embedded system).