1. A method of labeling context slices of a storyline of a user's movements, the method comprising: receiving a plurality of context slices derived from associated context data collected from a plurality of observation sources; and for each of the plurality of context slices: determining an uncertainty in a location of the slice based on a type of observation source from which the associated context data originated; identifying a set of candidate labels based on context data associated with the context slice, each candidate label matching the location of the slice within the predetermined uncertainty, the candidate labels each comprising semantic data describing the context data associated with the context slice, the semantic data selected from a group consisting of geography, venue, and activity; ranking the set of candidate labels by likelihood; applying one or more of the candidate labels to the context slice; and storing a correspondence between the applied one or more labels and the context slice.