The document defines and describes key properties of ellipses, including that an ellipse is the set of all points where the sum of distances from two fixed foci is a constant. It provides the standard equation forms for ellipses with horizontal and vertical major axes when the center is at (0,0), and then extends this to ellipses with an arbitrary center (h,k). Key properties defined include the lengths of the semi-major and semi-minor axes, the distance between the center and foci, and the Pythagorean relationship between these values. Examples are given to assess understanding of writing the standard equation for an ellipse given properties like the vertices and foci.