A lattice polygon is a shape in the plane bounded by a sequence of line segments $\overline{v_1 v_2},\ldots,\overline{v_{k-1} v_k}$, where the vertices $v_i$ have integral coordinates. Georg Alexander Pick described a relation between the area of the polygon and the number of lattice points contained in the polygon by a formula which is now known as Pick's Theorem. Ehrhart later generalized this result to higher dimensions, which is now an important tool in the field of Geometry of Numbers.