SWAT is an acronym for Special Weapons and Tactics, and is the term that describes a unit of a city police force or a county sheriff's department in the United States specially equipped and trained to deal with high-risk situations that would be too dangerous for patrol officers to deal with.
The nearest equivalents to SWAT in countries other than the United States are the national gendarmeries in various countries in Europe, including the French Gendarmerie and the Italian carabinieri. The key difference is that SWAT is a specialized team of police officers or sheriff's deputies trained in military weapons and infantry assault tactics, while still answerable to a local police chief or sheriff. European gendarmeries exist as separate national police forces. Whilst in Australia they have Special Operations Group and in New Zealand the Special Tactics Group. Both these units worked together during the 2000 Olympics in Sydney.
There is much discussion on the Police state level of militarization of the local law enforcement including "no knock raids" and automatic asset forfeiture without trial as part of the War on Drugs and the War on Terror. The most well known of the many books on the subject of the overuse of the SWAT teams is from Radley Balko, a policy analyst at the Cato Institute, authored Overkill: The Rise of Paramilitary Police Raids in America.