# H2

H2, H02, or H-2 may refer to:

## Arts and media

* Armenia 2 (H2), a private television company broadcasting in Armenia and Nagorno-Karabakh
* H2 (A&E Networks), the rebranded name of the former channel History International
** H2 (American TV channel), the American version of the channel
* H2 (manga), a baseball manga by Mitsuru Adachi
* Halo 2, a video game for the Xbox, created and developed by Bungie
* Halloween II (2009 film), initially abbreviated to H2
* Hollywood Squares, referred to as H$^2$ informally during the 2002–2004 seasons

## Computing

* <h2></h2>, level 2 heading markup for HTML Web pages, see HTML element#heading
* H2 (database), an open-source Java SQL database-management system
* DSC-H2, a 2006 Sony Cyber-shot H series camera
* HTTP/2, major revision of HTTP, often abbreviated in discussions as h2, and identifying itself to other servers as h2 in TLS negotiation or h2c in the HTTP Upgrade header
* LGA 1155 CPU socket, also known as Socket H2

## Roads and transportation

* Interstate H-2, a highway in Hawaii, located on the island of Oahu
* London Buses route H2

## Science and mathematics
### Biology and medicine

* ATC code H02 Corticosteroids for systemic use, a subgroup of the Anatomical Therapeutic Chemical Classification System
* British NVC community H2, a heath community in the British National Vegetation Classification system
* Histamine H$_2$ receptor
* Prostaglandin H2
* H-2, the Major histocompatibility complex of the mouse (equivalent of the Human Leukocyte Antigens)
* $H^{2}$ or $h^{2}$, wide- or narrow-sense heritability

### Chemistry

* H$_2$, the chemical formula for hydrogen gas (dihydrogen)
* Deuterium (Hydrogen-2, H-2, $^2$H), the isotope of hydrogen with one proton, one neutron, and one electron

### Other uses in science and mathematics

* H II region, a region of interstellar atomic hydrogen that is ionized
* The Hardy space H$^2$

## Vehicles
### Air and space

* H-II, a family of Japanese liquid-fueled rockets
** H-IIA
** H-IIB
** H-II Transfer Vehicle, a Japan Aerospace Exploration Agency uncrewed spacecraft
* H-2 MUPSOW, a precision-guided glide bomb manufactured by Pakistan
* Landgraf H-2, an American single-seat twin-rotor helicopter produced in 1944
* Standard H-2, a U.S. Army reconnaissance plane produced in 1916

### Automobiles

* Haval H2, a Chinese subcompact SUV
* Hummer H2, an American full-size SUV

### Motorcycles

* Kawasaki H2 Mach IV, 1970s two-stroke motorcycle
* Kawasaki Ninja H2, 2010s supercharged motorcycle

### Rail

* LB&SCR H2 class, a British LB&SCR locomotive
* GNR Class H2, a class of British steam locomotives
* LNER Class H2, a class of British steam locomotives
* H02 locomotive (Germany), a high-pressure steam locomotive made in 1930
* Saxon XII H2, a German steam locomotive produced in 1922
* PRR H2, a model within the American PRR locomotive classification
* H2, designation for METRORail Siemens S70 light rail vehicles

### Sea

* HMAS Success (H02), a Royal Australian Navy Admiralty S-class destroyer completed in 1918
* HMS Exmouth (H02), a British Royal Navy E-class destroyer commissioned in 1934
* HMS H2, a British Royal Navy H class submarine commissioned in 1915
* USS H-2 (SS-29), a U.S. Navy H-class submarine commissioned in 1913

## Other uses

* *h₂, one of the three laryngeals in the reconstructed Proto-Indo-European language
* H-2 Air Base, a military air base in Iraq
* H2 (classification), a para-cycling classification
* H-2A Visa, a United States visa for temporary or seasonal agricultural work
* H2, the second half of the business year
* H2 lamp, a halogen vehicle headlamp no longer manufactured
* H2, a model of hurricane tie manufactured by Simpson Strong-Tie Co.
* Sky Airline (IATA code H2)
* Area H2, an Israeli-controlled area under the Hebron Protocol
* H2 as the nickname for New Zealand civil servant Heather Simpson