Working with Digital Elevation Models and their derived products means dealing with geographic data. But what characterizes geographic data? What defines it? This is the primary focus of this chapter, which also describes the formats in which such data are represented, discusses key aspects of their symbology, and introduces related concepts such as temporality, projection systems, and spatial referencing. Particular attention is given to data format conversion operations, including transformations from vector to raster and vice versa, along with the implications involved.