AF

• A-F Records, Pittsburgh, Pennsylvania
• Almost Family, US TV series

European

• ÅF, a Swedish technical consulting company
• AF Gruppen, a construction company, Norway
• Action Française, a French political movement
• Air France, IATA code and stock symbol
• Anarchist Federation (British Isles)

International

• Abercrombie & Fitch, A&F, US clothing shops
• The Adaptation Fund, for climate change adaptation, UN
• Adventist Forums, of Seventh-day Adventists

Elsewhere

• American Freightways, US trucking company, merged into FedEx Freight

• Académie française, for French language matters
• Alliance Française, promoting French language and culture

• Acronym Finder, an online database

• Afrikaans language (ISO 639-1 language code AF)
• "...as fuck", meaning "very", in SMS language

• Amniotic fluid
• Atrial fibrillation, an abnormal heart rhythm

• AF Guardian, a US Navy warplane
• Air force
• Armed forces
• A US Navy hull classification symbol: Provisions store ship (AF)

• Afghanistan, by 2-letter ISO, FIPS 10-4, LOC MARC and obsolete NATO country code
  • .af, the top-level Internet domain for Afghanistan
• Agra Fort railway station, Rawatpara, India

Acoustics and communications

• Amplify-and-Forward, a scheme of relay channel
• Alternative frequency
• Audio frequency

Units of measure

• Acre-feet
• Attofarad

Visual arts

• Autofocus, of a camera
• Anisotropic filtering

Other uses in science and technology

• Af, the Köppen climate classification for a tropical rainforest climate
• Across flats (A/F), a measure of hexagonal nut flat size
• Advanced Format, large hard disk sectors
• Anaerobic filter, a type of anaerobic digester
• Arcuate fasciculus, a nerve bundle in the brain

• Alabama and Florida Railway (reporting mark AF)
• Anno Fascista, a year in the Italian Fascist calendar