Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for presence determination. One of the methods includes for one or more user devices having one or more associated users, determining a current location of a user, wherein the current location is associated with a particular space of a plurality of different spaces, wherein the determining includes: computing a plurality of location results, wherein each location result is computed using a distinct process of a plurality of processes; and evaluating the plurality of location results to determine a current space of the user; wherein the determining is performed by one or more of, a particular user device, a terminal device, or a server system.