Territory is a type of resource. It is key geographical locations in an environment that can be used for tactical or logistic advantage.
Possession of territory can lead to strategic dominance, increased pressure, fights for resources and advantage. Unlike other resources, territory is usually fixed to a world. Ownership of it requires that one or more of the players tools (such as his doll) be present in the territory, and when he moves then he loses it. Territory may also define boundaries (like the line of scrimmage in NFL), defining where tools can legally be placed or other conditional rules (such as kicking the ball out of bounds).
Other games test the player to find the optimal use of territory rather than its possession. In Sim City the challenge is to use territory most productively to make an awesome city. Real time strategy games mix both possession and optimal use (finding and resources and figuring out the logistics of using them).
Typical territorial resources include gates, choke points, high ground, yardage, goal lines, key squares, resource production areas, seat position (in Poker), cover and so forth. It is either nodal or contiguous, a property inherited from the environment.
