In this chapter, we shall present an overview of computer architecture from an academic standpoint, and explain the major principles behind today’s computers. We shall observe that there are two perspectives in computer architecture. We can look at computer architecture from the point of view of software applications. This point of view is sometimes referred to as architecture in literature. It is very important for students of computer architecture to study computer architecture from the viewpoint of a software designer because they need to know about the expectations of software writers from hardware. Secondly, it is also important for software writers to know about computer architecture because they can tailor their software appropriately to make it more efficient. In the case of system software such as operating systems and device drivers, it is absolutely essential to know the details of the architecture because the design of such kind of software is very strongly interlinked with low level hardware details.