Reconnaissance (US Army FM 7-92; Chap. 4)
In military operations, reconnaissance or scouting is the exploration outside an area occupied by friendly forces to gain information about natural features and other activities in the area.
Examples of reconnaissance include patrolling by troops (skirmishers, long-range reconnaissance patrol, U.S. Army Rangers, cavalry scouts, or military intelligence specialists), ships or submarines, manned or unmanned reconnaissance aircraft, satellites, or by setting up observation posts. Espionage normally is not reconnaissance, because reconnaissance is a military's special forces operating ahead of its main forces; spies are non-combatants operating behind enemy lines.
Often called recce (British, Canadian and Australian English) or recon (American English), the associated verb is reconnoitre or reconnoiter.