This paper gives an overview of the components that have to be taken into account for automatic situation recognition. Automatic situation recognition in complex situations enhances situation awareness of decision makers. The technical basis for achieving human situation awareness is provided through data fusion. Because of this connection, there exist unified models which combine both situation awareness and data fusion. One of these unified models is reviewed here. We also explain our interpretation of the term situation recognition and conclude that the first challenge is to find a suitable formalization of the term situation. Then, the basic requirements of a formalized description of a situation are extracted from general definitions of a situation. A possible formalization of a situation, which recently appeared in literature and covers the requirements extracted before, is reviewed.