Patrolling is a military tactic. Small groups or individual units are deployed from a larger formation to achieve a specific objective, such as reconnaissance or security, and then return. The tactic of patrolling may apply to ground troops, armored units, naval units, and combat aircraft. The duration of a patrol can vary from a few hours to seve... Found on http://en.wikipedia.org/wiki/Patrolling
(from the article `police`) To be effective, police forces must be in close proximity to the citizens they serve. The first and most basic means of maintaining that close ... Found on http://www.britannica.com/eb/a-z/p/29