Every plane has 3 or more. There is a projective (or affine) plane with only 3 points.

Projective motion is any motion defined in two dimensions. For example, if we mathematically project the three-dimensional path of a flying airplane onto a flat plane, the result is projective motion. The three-dimensional path was projected (thus the term) onto the flat plane..

Parallel lines in the Euclidean plane do not intersect but all parallel lines in the projective plane intersect at the point at infinity.

Arnold Emch has written:

'An introduction to projective geometry and its applications' -- subject(s): Accessible book, Analytic Geometry, Geometry, Analytic, Geometry, Projective, Plane, Projective Geometry

'Mathematical models' -- subject(s): Mathematics, Study and teaching

Egbert Brieskorn has written:

'Plane algebraic curves' -- subject(s): Algebraic Curves, Plane Curves, Projective Geometry