In military tactics, a patrol is a sub-subunit or small tactical formation, sent out from a military organization by land, sea or air for the purpose of combat, reconnaissance, or a combination of both. The basic task of a patrol is to follow a known route with the purpose of investigating some feature of interest or, in the assignment of a fighting patrol to find and engage the enemy. A patrol can also mean a small cavalry or armoured unit, subordinate to a troop or platoon, usually comprising a section or squad of mounted troopers, or two AFVs
In non-military law enforcement, patrol officers are law enforcement officers assigned to monitor 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.
Law enforcement patrols don’t always just enforce the laws during the patrols. They also try and have community relations, will investigate traffic accidents and transport criminals. They will go to schools to talk about their jobs or about drugs and safe driving. In some large cities, the police chief will go around to meet and talk with business owners, residents or anyone in the city.