1. A system for displaying information, comprising: a) an information structure having a plurality of semantic entities, each semantic entity having: (1) a navigable link to at least one other semantic entity; (2) a graphic object for representing the semantic entity on a display screen; b) a display window having a variably resizable display area, and a selected information density; and c) a display engine that displays graphics objects of a selected number of semantic entities, the semantic entities selected from the information structure in accordance with the selected information density.