Given a line l (resp. a plane Π‎) and a point P not on l (resp. Π‎), the projection of P on l (resp. Π‎) is the point N on l (resp. Π‎) such that PN is perpendicular to l (resp. Π‎). The length |PN| is the minimal distance from P to any point of l (resp. Π‎). The point N is called the foot of the perpendicular from P to l (resp. Π‎). This map from points P to l (or Π‎) is called orthogonal projection. See also vector projection.