ATT may refer to:

• AT&T, an American telecommunications company
• Amadou Toumani Touré, President of Mali
• American Telephone & Telegraph, a former telecommunications company
• American Tobacco Trail
• American Top Team, a mixed martial arts team based in Florida
• Arms Trade Treaty, A UN treaty to control the illicit trade of weapons
• Association of Taxation Technicians, a United Kingdom professional association
• ATI Tray Tools - freeware program developed by Ray Adams for ATI Radeon video cards
• Atmautluak Airport (IATA: ATT), an airport in Alaska
• The National Rail code for Attadale railway station, United Kingdom
• Attorney at law
• In biology, the name of a set of bacterial and bacteria-infecting virus (bacteriophage) genes involved in prophage integration.
• Attitude (disambiguation)
• Authorization to Transport, a permit issued in Canada to transport Restricted and Prohibited firearms

Attorney may refer to:

• Attorney at law, a lawyer in some countries
• Attorney general, the principal legal adviser to a government
• Attorney-in-fact, a person authorised to act on someone else's behalf in a legal or business matter by a power of attorney
• Attorney (England and Wales), a person, who may be but is not necessarily a lawyer, who is authorised to act on someone else's behalf in either a business or a personal matter

The Scandinavian clan or ætt (pronounced in Old Norse) was a social group based on common descent or on the formal acceptance into the group at a þing.

Die Abkürzung ATT steht für:

• AT&T, einen nordamerikanischen Telekommunikationskonzern
• Amadou Toumani Touré, den Präsidenten Malis

ATT peut faire référence à :

• American Telegraph and Telephon, une compagnie de téléphonie américaine,
• Amadou Toumani Touré, le président du Mali

Ätt är en beteckning på flera liktydliga korporationer, som gemensamt har att gruppen sammanbinds av släktskap, börd,  bördsrätt och att gruppen uppstått under uråldrig tid. Ätt används också för att beteckna kungliga och adliga släkter oavsett ålder på dessa.

AT&T (ang. American Telephone and Telegraph) – amerykańskie przedsiębiorstwo telekomunikacyjne. Notowane na New York Stock Exchange: . AT&T było przez pewien czas największym na świecie przedsiębiorstwem świadczącym usługi telefoniczne oraz największą siecią telewizji kablowej. W jego laboratoriach (Bell Labs) powstał m.in. system operacyjny Unix, języki C, C++ i AWK, a także tranzystor. Jedenastu pracowników tej korporacji otrzymało Nagrodę Nobla.