In
mathematics, a
projective plane is a geometric structure that extends the concept of a
plane. In the ordinary Euclidean plane, two lines typically intersect in a single point, but there are some pairs of lines (namely, parallel lines) that do not intersect. A projective plane can be thought of as an ordinary plane equipped with additional "points at infinity" where parallel lines intersect. Thus
any two lines in a projective plane intersect in one and only one point.