Linked from
The 35 pages that link to Kepler orbit, each with the reason it gives.
Orbital eccentricityNarrower topic: Its conic-section paths are classified by eccentricity.
Vis-viva equationNarrower topic: The vis-viva relation follows from this two-body orbital model.
Orbital maneuverNarrower topic: It provides the baseline orbit that a maneuver changes.
Lunar theoryNarrower topic: It supplies the baseline ellipse that lunar theory modifies.