thumb|300px|right|A52 Oste, a modern [[Oste class fleet service ship|Oste class ELINT and reconnaissance ship, of the German Navy]]
Reconnaissance (also scouting) is a military and medical term denoting exploration conducted to gain information. Militarily, its shorthand Canadian and British form is recce (), its American usage form is recon (). The associated, linguistic forms are the verb reconnoitre in British spelling, and reconnoiter in American spelling; informally, recce and recon are used as a verb.

Militarily, reconnaissance is the active seeking to determine a foe's intentions by collecting and gathering information about an enemy's composition and capabilities along with pertinent environmental conditions, via direct observation, usually by scouts or military intelligence soldiers especially trained in critical surveillance.

Reconnaissance is part of combat intelligence, and contributes to, and is managed by, the government-level intelligence cycle management. Compare to counterintelligence and surveillance, which are the passive gathering of data and information. Special reconnaissance is the reconnaissance sub-activity of clandestinely collecting data and information by people and with technology behind enemy lines.

Civil uses of the term reconnaissance occur in geology, the "examination or survey of the general geological characteristics of a region", and in computer networking and security it is an "exploration or enumeration of network infrastructure including network addresses, available communication ports, and available services."

Military reconnaissance

Examples of military reconnaissance include patrolling by troops, ships, submarines, or aircraft, or by setting up covert observation posts. Reconnaissance may also be carried out by satellites or unmanned aircraft.
Espionage normally is not reconnaissance, because reconnaissance is a military force's operating ahead of its main forces; spies are non-combatants operating behind enemy lines.

U.S. military reconnaissance acronyms are: SALT (size, activity, location, and time), SALUTE (size, activity, location, uniform, time, equipment), SAM & DOC (strength, armament, movement, deployment, organization, communications).

Elements

• Spacial: is the reconnaissance of any celestial bodies in space by use of spacecraft and satellite photography.

• Aerial: the reconnaissance by unmanned or manned aerial vehicles, or aircraft.

• Terrestrial: is a type of reconnaissance that is employed along the elements of ground warfare. It sometimes used in conjunction with amphibious reconnaissance when a force commander's areas of responsibility (AOR) covers an littoral area. Three types of 'ground recon' are characterized by the depth of penetration required, in terms of time, risk coordination, and support requirements, (1) close, distant, and deep.

• Naval: the reconnaissance of oceanic brown, green, and blue waters.

Reconnaissance in force

Some military elements tasked with reconnaissance are armed only for self-defence, and rely on stealth to gather information. Others are well-enough armed to also deny information to the enemy by destroying their reconnaissance elements.
Reconnaissance in force (RIF) is a type of military operation used specifically to probe an enemy's disposition. By mounting an offensive with considerable (but not decisive) force, the commander hopes to elicit a strong reaction by the enemy that reveals its own strength, deployment, and other tactical data. In modern warfare, key weapon systems such as surface-to-air missile batteries, radar sites, artillery, and so forth can give their location away to everyone for miles around when actively fighting. The RIF commander retains the option to fall back with the data or expand the conflict into a full engagement.
Reconnaissance by fire (or speculative fire, "spec fire") is a tactic which applies a similar principle. When not trying to be stealthy, reconnaissance units may fire on likely enemy positions to provoke a reaction. In the Iraq War, the irregular forces use a similar tactic, in which they brandish weapons or purposely draw suspicion, in order to learn about the rules of engagement of opposing forces.

Ground reconnaissance by regular or special forces

Ground reconnaissance is carried out by a variety of troops from different Arms and Services for different purposes. This type of reconnaissance is related to the need for knowledge of the enemy by different echelons of command. The rank superiority in the military hierarchy is related to the distance from the FEBA (Forward Edge of Battle Area) that the information about the enemy usually needs to come from as the officer seeks to find and understand the decisions and actions of their opposites.
Special reconnaissance (SR) is defined, by the US, to be conducted by special operations troops, most commonly United States Army Special Forces, United States Marine Corps Force Reconnaissance, United States Air Force Special Tactics and United States Navy SEALs, who operate deep behind enemy lines, usually but not always in uniform. The British equivalents, including the Special Air Service, Special Boat Service, Special Reconnaissance Regiment and also 16 Air Assault Brigade's Pathfinder Platoon and the Royal Marines' Mountain Leaders.
Soviet and Russian equivalents include Spetsnaz. Israeli "reconnaissance units" such as Sayeret Matkal are often more associated with direct action than reconnaissance, but they obviously have that capability. SR units can reach the area of operations by numerous means, including parachuting, infiltration by foot or tactical vehicles, helicopters, and surface and subsurface access from water.

SR is a strategic mission, responsible to regional or national commands. In both cases, the reconnaissance asset, to the maximum extent possible, remains clandestine, in enemy territory, or, when long-range sensors can be used, outside it. SR does have a Direct Action capability if required. It is not unusual for their troops to operate 250 km forward of FEBA.

Medium Reconnaissance is usually performed by specialist reconnaissance units, which are sometimes called cavalry, since reconnaissance was a traditional cavalry role and because these units are usually mounted and highly mobile. These units usually provide reconnaissance between the forward edge of battle area and the rear of the zone covered by long range/strategic ground reconnaissance. Units that provide a medium reconnaissance capability are usually organic to or attached to division and corps level units. These units are often armoured, highly mobile, have excellent communications and are often issued with short and long range sensors, such as thermal imagers, ground survelillance radar and seismic sensors.
Medium reconnaissance units are commonly organised with organic armour, dismount troops (scouts/assault troopesr), indirect fire support such as mortars or sometimes artillery. In effect these units are often miniature combined arms battle groups. Medium reconnaissance units in common with the cavalry of old often carry out, screening, covering force, pursuit and exploitation roles in addition to pure reconnaissance.

Short range reconnaissance is usually performed by platoon and company sized elements organic to arms units, such as the recon/scout platoons in infantry battalions or recon troops in armoured regiments/battalions or ISTAR companies organic to brigades. Short range reconnaissance covers the ground between the forward positions to the rear of the zone covered by medium reconnaissance assets.

Deep reconnaissance

Deep reconnaissance (also known as long-range reconnaissance, or deep reconnaissance) is the depth of reconnaissance that pertains to battlespace. Deep recon is conducted mainly in deep operations; this usually means 120-200 miles from any friendly ground forces, behind enemy lines. Military commanders primarily employ deep reconnaissance teams (such as The British 22nd Special Air Service (22SAS), Air Force Special Operations Special Tactic Teams, Army Special Forces and reconnaissance teams, Navy Special Operations Forces, Marine Corps's Force Recon, etc.) into the commander's Area of Interest to 'shape' and describe the battlespace, allowing him to adjust or plan missions for future operations.

Long-range reconnaissance, also called Long Range Surveillance (LRS), is defined as in small groups, in uniform, moderately far behind the enemy lines. While LRS units may direct air or artillery strikes against enemy positions, they strive to be unobserved, and have only self-defense, not DA, capability. They may use unorthodox means of entry, such as swimming in from a submarine or specialized parachuting techniques (e.g., HAHO and HALO, High-Altitude High-Opening and High-Altitude Low-Opening, respectively). These troops may operate 100 km forward of FEBA. Units designated to carry out this role include: LRSU (US Army); 4/73 Sphinx Special Observation Battery and the Honourable Artillery Company
(UK Army); and Fernspähkompanie German Army.

Dedicated ground reconnaissance units (known in the US Army as Cavalry) provide both an information gathering and a screening force service to the other Arms and Services engaged in combat. Specialist scout units may operate as far as 25-50 km forward of the FEBA.

While almost every frontline military unit is sometimes assigned to do limited patrolling or surveillance of one kind or another, this kind of stealthy scouting far from friendly bases is a particularly dangerous mission. Light cavalry often served this purpose in the past, and modern militaries make this a special forces mission. When the recon team is unfamiliar with the terrain, recruitment of local guides can be very desirable for these kind of missions.

In US practice, combat battalions have reconnaissance or scouting platoons, forces typically of 20-40 men, but sometimes twice that size, that can probe beyond the main line of the unit
. Brigades and divisions have separate Long Range Surveillance units
, which can go deeper beyond the front line; the structure of such units is changing as the US Army reorganizes into a Brigade combat team model with enhanced reconnaissance. As of 2007 though the Scout specialists were being removed from some US brigades such as the Stryker Brigade Team.
Dedicated scouts serving with infantry, tank, artillery, engineer, or logistics units will generally position themselves about 5 km in advance of the forward units where possible. Different Arms and Service scouts have different tasks to perform for their higher echelons of command. For example the engineer reconnaissance detachments will try to identify difficult terrain in the path of their formation, and attempt to reduce the time it takes to transit the terrain using specialist engineering equipment such as a pontoon bridge for crossing water obstacles.

See also

• Armoured Reconnaissance

• Intelligence, Surveillance, Target Acquisition, and Reconnaissance

• U.S. Army Long Range Surveillance

• Joint Functional Component Command for Intelligence, Surveillance and Reconnaissance

• Surveillance aircraft

• Airborne pathfinders

• UN fact-finding missions