A plane equation is a mathematical representation of a flat, two-dimensional surface in three-dimensional space. It is typically expressed in the form Ax + By + Cz + D = 0, where A, B, and C are the coefficients that define the plane's orientation, and D is a constant. The variables x, y, and z represent the coordinates of any point on the plane. To find the equation of a plane, you need a point on the plane and a normal vector, which is perpendicular to the surface. The normal vector's components correspond to the coefficients A, B, and C in the plane equation. This concept is essential in fields like geometry, physics, and computer graphics.