Location Theory and the Ordered Median Function.- Mathematical Properties of the Ordered Median Function.- The Continuous Ordered Median Location Problem.- The Continuous Ordered Median Problem.- Bisectors.- The Single Facility Ordered Median Problem.- Multicriteria Ordered Median Problems.- Extensions of the Continuous Ordered Median Problem.- Ordered Median Location Problems on Networks.- The Ordered Median Problem on Networks.- On Finite Dominating Sets for the Ordered Median Problem.- The Single Facility Ordered Median Problem on Networks.- The Multifacility Ordered Median Problem on Networks.- Multicriteria Ordered Median Problems on Networks.- Extensions of the Ordered Median Problem on Networks.- The Discrete Ordered Median Location Problem.- and Problem Statement.- Linearizations and Reformulations.- Solution Methods.- Related Problems and Outlook.