The CPU or Central Processing Unit, is the heart of your computer. Depending on what CPU you have or plan to get you will need to match the right motherboard to it. Inorder to select the right motherboard you will need to know what type of connector your CPU needs. The different types of connectors and what CPU's use them will be discussed below:
[Super] Socket 7 - This is one of the older types of connectors that is still being manufactured. This Socket was first made for Intel's Pentium line of CPU's. AMD made their K6-2 and K6-3 line of CPU's for this type of socket also. Intel's Pentium MMX CPU's only changed the voltage levels going to and from the CPU so the same socket was kept. The 'Super' prefix usually indicates that the motherboard is capable of accepting MMX style Pentiums and AMD K6-2 and K6-3 CPU's.
Intel's next line of CPU's used a slot. The slot is called 'Slot 1'. The slot idea was to give the newer, faster, and HOTTER CPU's more surface area to cool off, and allow a place to put the onboard but not on-die (built in to the CPU) cache. The cache needed to be on the CPU side of the connector since it would be running faster than the motherboard but only originally half as fast as the CPU. The slot also allowed these larger CPU's to not use so much space on the motherboard.
Due to some sort of rivalry/incompatibilities with Intel, AMD developed the Slot A connector for their Athlon CPU's. Slot A is not compatible with Slot 1.
Socket 370 was first made for Celerons. The first Celerons had no cache and therefore had no need of the slot style connector. When Celerons got to have cache they were moved to Slot 1 connections. Once the Pentium III's had their cache brought to the full speed of the CPU and then put on the die with the CPU (on the same piece of silicon) there was no need of the huge card. The P3's were then moved back to the socket 370 connector. But there was a catch just like with Pentium MMX's of old, you needed a motherboard designed for the new CPU's, since there was something different about pin usage and/or voltages. The different names for the sockets are PPGA (Processor Pin Grid Array) for the old style connections and FC-PGA (Flip Chip Pin Grid Array).
Socket A - AMD followed suit on moving the cache to on-die and moved back to a socket. Again, due to rivalry/incompatibilities they developed their own socket called 'Socket A'. And their new Athlons codenamed (nicknamed?) Thunderbird and their lesser siblings the Duron both work off of a motherboard with Socket A.
Socket 478 - Intel's revised socket for Pentium IV's with the Northwood core. The easiest way to identify this new socket is that the chip and its socket are not much bigger than a quarter.