A two-dimensional affine geometry constructed over a finite field. For a field F of size n, the affine plane consists of the set of points which are ordered pairs of elements in F and a set of lines which are themselves a set of points. Adding a point at infinity and line at infinity allows a projective plane to be constructed from an affine plane. An affine plane of order n is a block design of the form (n^2, n, 1). An affine plane of order n exists iff a projective plane of order n exists.