When you look at a map, you are looking at a two-dimensional representation of a 3D object (the Earth). Because we are, essentially, 'losing' a dimension when we create a map, no map is a perfect representation of the Earth. All maps have some distortion.
The distortion depends on what projection (a method of representing the earth's surface on a two dimensional plane) you use. In this chapter, we'll talk more about what projections are, why they're important, and how we can use them in OpenLayers. We'll also cover some other fundamental geographic principles that will help make it easier to better understand OpenLayers.
In this chapter, we will cover the following topics:
Concept of map projections
Types of projections
Latitude, longitude, and other geographic concepts
The OpenLayers projection class
Transforming coordinates
Projections in context of raster layers
Projections using vector layers
Let's get started!