Do not confuse slots with bays. Bays are sites within the computer where you can install disk drives. Typically, slots are in the back of the computer and bays are in the front.
Processor Sockets and Slots Describes socket and slot standards and other issues related to mating processors to the system motherboard. This page is from "The PC Guide."
Processor Physical Characteristics Discusses the physical properties of processors. Includes information on processor manufacturing, physical chip characteristics, power and voltage, cooling and packaging, and sockets and slots.