Observation is the influence of terrain on reconnaissance, surveillance, and target acquisition capabilities. FOF is the effect of terrain on weapons effectiveness. Concealment is protection from air and ground observation. Cover is protection from the effects of fire. Both are vital for protection from hostile fire.
Obstacles are natural and manmade terrain features that stop, impede or divert military movement.
Key terrain is any feature or area the seizure or control of which offers a marked tactical advantage. AAs are routes by which a force may reach key terrain or an objective. If engineer terrain support is unavailable, terrain should be evaluated through a map analysis supplemented by reconnaissance. DMA produces specialized maps, overlays and data bases to aid in map based evaluations. Weather in the AO is analyzed to determine its effects on friendly and threat operations.