What Does PCI Slot Mean?
A PCI slot is a built-in slot on a device that allows for the attachment of various hardware components such as network cards, modems, sound cards, disk controllers and other peripherals.
Techopedia Explains PCI Slot
These days, the PCI slot has largely become obsolete. First, new standards have emerged for making the actual device connections, and secondly, new protocols have replaced some of the traditional ones for connecting to the modernized bus.