AH

AH (also Ah or ah) may refer to:

• Ah (digraph), a digraph used in Taa orthography
• Adolf Hitler
• After-hours trading in stock trading
• Air handler, or air handling unit (AHU), a device used to condition and circulate air
• Albert Heijn, a Dutch supermarket chain owned by Ahold
• Ampere-hour, a unit of electric charge
• Anhui, a Chinese province
• Attohenry (aH), an SI unit of inductance
• Auction house
• Austria–Hungary, a former European empire
• Hijri year (Anno Hegirae) in the Islamic calendar
• Adenomatous hyperplasia; see endometrial adenomatous hyperplasia and atypical adenomatous hyperplasia

In aviation:

• AH-1 Cobra, a model of attack helicopter
• AH-64 Apache, a model of attack helicopter
• Artificial Horizon, a cockpit instrument (Aviation)

In computing:

• Ah (computer virus), a DOS computer virus
• AH register, the high byte of an X86 16-bit AX register
• Authentication Header, a part of the IPsec protocol suite

In entertainment:

• "Ah" (song), a song by Japanese J-Pop and rock band Superfly
• A-ha, a New Wave/Synthpop band from Norway
• Alternate History, a subgenre of speculative fiction
• Arcana Heart. a video game series
• Avalon Hill, makers of military-themed board games