The shapes of objects usually match the intrinsic properties of the objects (e.g., the
cylinder shape for a data store, an actor represented by a stick figure, etc.). There is a
tendency to use realistic, possibly three-dimensional symbols for concrete and
tangible objects (e.g., cylinder, human figure, factory symbol, graphics of computers)
and to use simple, geometric shapes for abstract concepts (e.g., process, function,
component, etc.).