In this chapter, we quickly reviewed the layer structure inheritance, focusing on raster. Then, we talked about what raster data layers are, how they work, and what benefits you can get from using different sources to display your maps. We learned how to use the Microsoft Bing Maps layer, all API depending on tiles using OpenStreetMap data. We also discussed tiling in OpenStreetMap that use Spherical Mercator and how to create a map mashup with a layer switcher, mixing various layers and sources' types together. We didn't restrict the chapter to maps as it's possible to also use images unrelated to cartography.

In the next chapter, Using Vector Layers, we will see the concept of vector layer in-depth and the OpenLayers main classes for using them. Like for raster, you will discover not only their specific sources but also the various vector data formats and how to manipulate features and geometry.