In mathematics, an ellipse is a curve on a plane surrounding two focal points such that a straight line drawn from one of the focal points to any point on the curve and then back to the other focal point has the same length for every point on the curve.

An ellipse is the locus of all those points in a plane such that the sum of their distances from two fixed points in the plane, is constant. The fixed points are known as the foci (singular focus), which are surrounded by the curve. The fixed line is directrix and the constant ratio is eccentricity of ellipse. Eccentricity is a factor of the ellipse, which demonstrates the elongation of it and is denoted by ‘e’.