How to Create a Geospatial Map?

In the g i s world, which is a, ou know, geographic information system, they call it digital elevation models. What ii am take is just a simple grid, so matrix of values, a where every single point represents some elevation and they're evenly spaced. So you don't need a lot of code to make something like that. But what is the kind of data that you need to create something like that?