The motherboard of a computer is a very important component. The motherboard is the component that ties all of the other parts together. For the average person, the motherboard may not be something important to consider in a new computer - and most manufacturers do not allow much leeway in motherboard selection. High end computers however will take a great focus on motherboard selection because there are a number of factors that can affect performance.
Your motherboard not only holds your processor and RAM, but also the add-on cards you may have installed such as video cards, modems, wireless cards, and more. Most motherboards will have more than one type of expansion slot, PCI is an older type of slot that is still used today, and PCIeXpress (PCIe) is the latest type of slot available in multiple speeds. Older computers will have a single AGP slot used for video cards. If you are looking to upgrade your computer, finding out what kind of motherboard you have is very important to your upgrade options.