This chapter lays the groundwork that helps us to understand what Content Management Systems (CMS) are all about. First, it summarizes the whole idea of a CMS where it came from and what it looks like. This is followed by a review of the technology that is advocated here for CMS building. Next, we will take account of how the circumstances in which a CMS is deployed affect its design; some of the important environmental factors, including security, are considered. Finally, all these things are brought together in an overview of CMS architecture. Along the way, Aliro is introduced—the CMS framework that is used for illustrating implementations throughout this book.