Imagine representing a mountain range, a weather map, or a satellite image using millions of tiny square tiles. Each tile stores exactly one number — perhaps a temperature, a height, or a land‑cover code. That grid‑of‑tiles idea is the raster model, and it is the simplest way to capture how something changes continuously across space. In this chapter we will see how these grids work, how to stop them from eating up all your hard‑drive space, and how to build three‑dimensional landscapes you can almost feel under your feet.