This chapter deals with the challenges of cartographic representation of a three-dimensional earth on two-dimensional maps. It explains the basic principles of projection, the distortions that arise, and the significance of scales and coordinate systems for orientation. Various projections—cylindrical, azimuthal and conical—are examined in terms of their advantages and disadvantages, with a focus on the question of which quality criteria (area, length or angle fidelity) can be met in each case. Special attention is paid to the Mercator projection and its importance for navigation, as well as to the Gall-Peters projection as an equal-area alternative. In addition, the UTM coordinate system is presented as a more precise method for small-scale representations. The discussion shows that there is no perfect two-dimensional map of the earth, but that each projection must be optimized depending on its intended use.