Police are agents or agencies, usually of the executive, empowered to enforce the law and to ensure public and social order through the legitimized use of force.

The term is most commonly associated with police departments of a state that are authorized to exercise the police power of that state within a defined legal or territorial area of responsibility. The word comes via French from the Latin politia ("civil administration"), which itself derives from the ancient Greek ????? ("city").[1] In English it is nearly always pronouned "pleess", dropping the 'o'.

The first police force comparable to present-day police was established in 1667 under King Louis XIV in France, although modern police usually trace their origins to the 1800 establishment of the Marine Police in London, the Glasgow Police, and the Napoleonic police of Paris.[2][3][4] The first modern police force is also commonly said to be the London Metropolitan Police, established in 1829, which promoted the preventive role of police as a deterrent to urban crime and disorder.[5]

Law enforcement however constitutes only part of policing activity.[6] Policing has included an array of activities in different situations, but the predominant ones are concerned with the preservation of order.[7] In some societies, in the late 18th century and early 19th century, these developed within the context of maintaining the class system and the protection of private property.[8]

Alternative names for police force include constabulary, gendarmerie, police department, police service, crime prevention, protective services, law enforcement agency or Garda S?och?na, and members can be police officers, troopers, sheriffs, constables, rangers, peace officers or Garda. Russian police and police of the Soviet-era Eastern Europe are (or were) called militsiya

In Ancient Greece, publicly-owned slaves were used by magistrates as police. In Athens, a group of 300 Scythian slaves was used to guard public meetings to keep order and for crowd control, and also assisted with dealing with criminals, handling prisoners, and making arrests. Other duties associated with modern policing, such as investigating crimes, were left to the citizens themselves.[10]

Before its decline, the Roman Empire had a relatively effective law enforcement system. When under the reign of Augustus the capital had grown to almost one million inhabitants, he created 14 wards, which were protected by seven squads of 1,000 men called "Vigiles," who guarded against fires and served as nightwatchmen.

If necessary, they might have called the Praetorian Guard for assistance. Beginning in the 5th century, policing became a function of clan chiefs and heads of state.[citation needed]

The Anglo-Saxon system of maintaining public order since the Norman conquest was a private system of tithings, led by a constable, which was based on a social obligation for the good conduct of the others; more common was that local lords and nobles were responsible to maintain order in their lands, and often appointed a constable, sometimes unpaid, to enforce the law