This wraps up our overview of the key concepts in the OpenLayers library. We took a quick look at the key components of the library from two different aspects—relationships and inheritance. With the Map class as the central object of any OpenLayers application, we looked at its main relationships to other classes including views, layers, overlays, interactions, and controls. We briefly introduced each of these classes to give an overview of primary purpose. We then investigated inheritance related to these objects and reviewed the super classes that provide functionality to most classes in the OpenLayers library—the Observable and Object classes. The Observable class provides a basic event mechanism and the Object class adds observable properties with a powerful binding feature. Lastly, we looked at the Collection class. Although this isn't part of the inheritance structure, it is crucial to know how one-to-many relationships work throughout the library (including the Map class relationships...