An ellipse is a geometric shape that looks like a stretched circle. It is defined as the set of all points where the sum of the distances from two fixed points, called foci, is constant. Ellipses can vary in size and shape, depending on the distance between the foci and the overall dimensions. In mathematics, the standard equation of an ellipse centered at the origin is \fracx^2a^2 + \fracy^2b^2 = 1, where a and b are the lengths of the semi-major and semi-minor axes, respectively. Ellipses are commonly found in nature, such as in the orbits of planets around the Sun and in the shapes of certain fruits.