OpenStack has a very modular design, and because of this design, there are lots of moving parts. It's overwhelming to start walking through installing and using OpenStack without understanding the internal architecture of the components that make up OpenStack. In this chapter, we'll look at these components. Each component in OpenStack manages a different resource that can be virtualized for the end user. Separating each of the resources that can be virtualized into separate components makes the OpenStack architecture very modular. If a particular service or resource provided by a component is not required, then the component is optional to an OpenStack deployment. Let's start by outlining some simple categories to group these services into.