H3

H3, H03 or H-3 may refer to:

Culture

• Happy Hustle High, a manga series by Rie Takada
• Halo 3, a video game by Bungie Studios for the Xbox 360
• H3 (film), a 2001 film about the 1981 Irish hunger strike

Science

• H₃ Triatomic hydrogen
• Hydrogen-3, H-3, ³H (a.k.a. tritium), an unstable isotope of hydrogen
• The trihydrogen cation, H₃⁺, one of the simplest polyatomic molecules
• ATC code H03 Thyroid therapy, a subgroup of the Anatomical Therapeutic Chemical Classification System
• British NVC community H3, a heath community of the British National Vegetation Classification system
• Histamine H3 receptor, a human gene
• Histone H3, a component of DNA higher structure in eukaryotic cells
• Disorders of eyelid in diseases classified elsewhere ICD-10 code
• <h3></h3>, level 3 heading markup for HTML Web pages, see HTML element#heading
• H3 cell phone charger, by Swedish company myFC, using water fuel cell
• *h₃, one of the three laryngeals in the reconstructed Proto-Indo-European language
• H-3, the Hekla 3 eruption, a huge volcanic eruption around 1000 BC

Transportation

• H3 Launch Vehicle, an expendable launch system under development by Japan Aerospace Exploration Agency
• H-3 Sea King, a United States Navy helicopter
• PRR H3, an American PRR 2-8-0 steam locomotive
• Standard H-3, an improved version of the 1916 Standard H-2 aircraft
• USS H-3 (SS-30), a 1914 United States Navy H-class submarine
• H3 Monks Way, a road part of the Milton Keynes grid road system
• HMS Grenville (H03), a 1935 British Royal Navy destroyer
• HMS H3, a 1915 British Royal Navy H class submarine
• Hummer H3, the smallest of the three Hummer models sold by General Motors
• Interstate H-3, a highway in Hawaii
• H-3 air base cluster located 435 kilometers from Bagdad in western Iraq. The main H3 airfield was originally built to support the H-3 oil pumping station.
• Highway H03 (Ukraine), a road in Ukraine
• The IATA code for Harbour Air Seaplanes, a charter airline based in Canada
• H3, a METRORail light rail vehicle

Other uses

• H3 (HTML), a text marked with 3rd level of importance
• H3 (pyrotechnics), a pyrotechnic composition
• H3 Pharmaceutical Chemistry, a higher paper for GCE 'A' level chemistry for Singapore students
• DSC-H3, a 2008 Sony Cyber-shot H series camera
• Hash House Harriers, an international group of non-competitive running, social and drinking clubs
• H3 or Harrison Number Three, an 18th-century marine chronometer
• H3 (lamp), an automotive halogen lamp
• The H3 hurricane tie manufactured by Simpson Strong-Tie Co.
• H3 Hardy Collaboration Architecture, a firm started by Hugh Hardy
• The LGA 1150 CPU socket, also known as Socket H3
• h3h3 Productions, a satirical comedy channel on YouTube