In this chapter we talked about the Layer class. We covered the concept of layers and the differences between base layers and overlay layers. We went in depth with the WMS Layer class. We discussed the Layer class properties and methods and were introduced to various layer subclasses.
Whew! This was all likely a lot to take in. We covered a lot of Layer classes individually, but we have not yet made a map with different types of Layer classes. This is one of the things that OpenLayers excels at, and is what drives map 'mash ups.' To understand how to go about putting different layer classes together though, we'll need to have a basic understanding of projections—the topic of our next chapter.