AT

AT or at may refer to:

Austria

 * Austria (ISO 2-letter country code)
 * .at, Internet country code top-level domain

United States

 * Atchison County, Kansas (county code)
 * The Appalachian Trail (A.T.), a 2,180+ mile long mountainous trail in the Eastern United States

Elsewhere

 * Antigua and Barbuda, World Meteorological Organization country code
 * Ashmore and Cartier Islands (FIPS 10-4 territory code, and obsolete NATO country code)
 * At, Bihar, village in Aurangabad district of Bihar, India
 * Province of Asti, Italy (ISO 3166-2:IT code)
 * Australia, LOC MARC code

Politics

 * Awami Tahreek a left-wing Pakistani political party

Computing

 * @ (or "at sign"), the punctuation symbol now typically used in e-mail addresses and tweets)
 * at (command), used to schedule tasks or other commands to be performed or run at a certain time
 * IBM Personal Computer/AT
 * AT (form factor) for motherboards and computer cases
 * AT connector, a five-pin DIN connector for a keyboard
 * The Hayes command set for computer modems (each command begins with the character string "AT")

Biology and medicine

 * Anaerobic threshold, in physiology
 * Análisis transaccional (Spanish for "transactional analysis"), a psychological method
 * Antithrombin, a small protein molecule
 * Ataxia–telangiectasia, an immunodeficiency disorder
 * Athletic training
 * Atrial tachycardia

Physics and chemistry

 * Astatine (symbol At), a chemical element
 * Ampere-turn (symbol A t), an International System of Units (MKS) unit of magnetomotive force
 * Attotesla (symbol aT), 10−18 tesla, an SI derived unit of magnetic flux density
 * Technical atmosphere (symbol at), a physical unit of pressure

Other uses in science and technology

 * Acceptance testing, in engineering
 * Appropriate technology, an ideological movement to scale technology to be appropriate to its context
 * Assistive technology, devices for people with disabilities
 * AT Protocol, a decentralized social network protocol by Bluesky
 * Anti-tank warfare
 * Automatic transmission, in vehicles

Other uses

 * At, a preposition
 * At (cuneiform), a cuneiform sign
 * At, 1/100 of a Lao kip, a unit of currency
 * Aarne–Thompson classification system, used to classify folktales
 * Archive Team, a digital preservation group
 * Aliança da Terra, a Brazilian non-governmental organization
 * Alternative Tentacles, an independent record label
 * Auckland Transport, New Zealand, a public transport agency
 * Audiotool, a Digital audio workstation
 * Autolinee Toscane, Italy, a public transport agency
 * Aviation electronics technician (United States Navy), a job specialty
 * Royal Air Maroc (IATA airline designator AT)
 * A US Navy hull classification symbol: Fleet tug (AT)