In military tactics, a patrol is often a small tactical grouping sent out by land, sea or air to perform a specific task. The basic task of a patrol is to follow a known route at regular intervals looking out for anything out of the ordinary — which if found will be reported or dealt with as appropriate. A patrol may also be a reconnaissance patrol, sent to investigate some feature of interest, or a fighting patrol (US combat patrol), sent to find and engage the enemy. A patrol can also mean a small cavalry or armoured unit, subordinate to a troop or platoon. A patrol usually comprises a section or squad of mounted troopers, or two AFVs (often tanks).
In law enforcement, patrol officers are uniformed police officers assigned to patrol specified geographic areas — that is, to move through their areas at regular intervals looking out for any signs of problems of any kind. They are the officers most commonly encountered by the public, as their duties include responding to calls for service, making arrests, resolving disputes, taking crime reports, and conducting traffic enforcement, and other crime prevention measures. A patrol officer is often the first to arrive on the scene of any incident; what such an officer does or fails to do at the scene can greatly influence the outcome of any subsequent investigation. The patrol officer, as the person who is in the field daily, is often closest to potential crime and may have developed contacts who can provide information.
Some elementary schools use the term patrol to refer to students who are selected to monitor safety in the classroom or to those students who assist crossing guards with safety of children crossing busy streets. Another common term for this use of patrol is hall monitor.
In Surf Lifesaving, volunteer patrol units monitor the beaches during the summer. In Australia and some other countries, the patrolled area is marked by red and yellow flags.
In Scouting, a patrol is six to eight children under the leadership of one of them, the basic unit of the Scout movement. The Patrol method is an essential characteristic of Scouting by which it differs from all other organizations, using the natural dynamics of the gang for an educational purpose.