Appalachian Mountains

Associated Press of Pakistan

.APP (filename), filename extension. Application for Symbian OS

Appalachian State University

Populist Party (United States), an American political party

American People's Party, an American political party

The Alan Parsons Project, a progressive rock band

Atom Publishing Protocol, a protocol for creating and updating web resources

Appleton, Wisconsin, in Amtrak's three-letter code

Austrian People's Party, an Austrian political party

Asia-Pacific Partnership

Amyloid precursor protein, a protein fragment associated with some neurological disorders

Alliance populaire progressiste, a Mauritanian political party

Anticlerical Progress Party REASON, a Polish political party

Asia Pulp & Paper

Appleby railway station, England, in National Rail's code

App is short for Application. It could be an abbreviation for: