H4, H04, or H-4 may refer to:

Science and mathematics

ATC code H04 H04A Glycogenolytic hormones H04AA Glycogenolytic hormones :H04AA01 Glucagon Glucagon is a peptide hormone, produced by alpha cells of the pancreas. It raises concentration of glucose and fatty acids in the bloodstream, and is considered to b ...

''Pancreatic hormones'', a subgroup of the Anatomical Therapeutic Chemical Classification System * Histamine H₄ receptor, a human gene *

Histone H4 Histone H4 is one of the five main histone proteins involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and a long N-terminal tail, H4 is involved with the structure of the nucleosome of the 'beads on ...

, a protein involved in the structure of chromatin in eukaryotic cells * Hydrogen-4 (H-4), an isotope of hydrogen * H₄, a

symmetry group In group theory, the symmetry group of a geometric object is the group of all transformations under which the object is invariant, endowed with the group operation of composition. Such a transformation is an invertible mapping of the amb ...

in the fifth dimension.

Technology

* H-4 SOW, a precision-guided glide bomb used by the Pakistan Air Force *

Halo 4 ''Halo 4'' is a 2012 first-person shooter video game developed by 343 Industries and published by Microsoft Studios for the Xbox 360 video game console. ''Halo 4''s story follows a cybernetically enhanced human supersoldier, Master Chief, a ...

, a video game created by

343 Industries 343 Industries is an American video game developer located in Redmond, Washington, part of Xbox Game Studios. Headed by Pierre Hintze, the studio is responsible for the ''Halo (franchise), Halo'' series of military science fiction games, origin ...

for the

Xbox 360 The Xbox 360 is a home video game console developed by Microsoft. As the successor to the original Xbox, it is the second console in the Xbox series. It competed with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generati ...

* Harrison Number Four, an 18th-century marine chronometer designed by John Harrison * Zoom H4 Handy Recorder, a handheld digital audio recorder * , level 4 heading markup for HTML Web pages, see HTML element#heading

Transport

Automobiles and roads

* H4, a halogen

headlamp A headlamp is a lamp attached to the front of a vehicle to illuminate the road ahead. Headlamps are also often called headlights, but in the most precise usage, ''headlamp'' is the term for the device itself and ''headlight'' is the term for ...

bulb * H4, development name of the Hummer HX concept car * H-4, shorthand for a 4-cylinder horizontally-opposed or "flat four" engine (not to be confused with an actual

H engine An H engine is a piston engine comprising two separate flat engines (complete with separate crankshafts), most often geared to a common output shaft. The name "H engine" is due to the engine blocks resembling a letter "H" when viewed from the fro ...

) *

H4 Dansteed Way The Milton Keynes grid road system is a network of predominantly national speed limit, fully landscaped routes that form the top layer of the street hierarchy for both private and public transport in Milton Keynes, Buckinghamshire. The system is ...

, a road in Milton Keynes, England

Aviation

* GEN H-4, a Japanese helicopter design *

Hughes H-4 Hercules The Hughes H-4 Hercules (commonly known as the ''Spruce Goose''; registration NX37602) is a prototype strategic airlift flying boat designed and built by the Hughes Aircraft Company. Intended as a transatlantic flight transport for use durin ...

(Spruce Goose), the largest flying boat ever built * H4, IATA code for Héli Sécurité Helicopter Airlines, based in France * H4, IATA code for Inter Islands Airlines, based in Cape Verde

Ships and submarines

* HMS ''H4'', a 1915 British Royal Navy H-class submarine * HMS ''Tenedos'' (H04), a 1918 British Royal Navy Admiralty S-class destroyer * USS ''H-4'' (SS-147), a 1918 United States Navy submarine

Trains

* GNR Class H4, a 1920 British 2-6-0 steam locomotive model

Other uses

* ''H4'' (film), a 2013 film * H-4 visa, issued by the U.S. Citizenship and Immigration Services *

British NVC community H4 __NOTOC__ NVC community H4 (''Ulex gallii - Agrostis curtisii'' heath) is one of the heath communities in the British National Vegetation Classification system. It is one of three communities which are considered transitional between the lowland dr ...

, a heath community in the British National Vegetation Classification system * H4 (classification), a cycling classification used in para-cycling * H-4, a huge eruption of the

Hekla Hekla (), or Hecla, is a stratovolcano in the south of Iceland with a height of . Hekla is one of Iceland's most active volcanoes; over 20 eruptions have occurred in and around the volcano since 874. During the Middle Ages, the Icelandic Nor ...

volcano around 2310 BC * H4, Houston

Hash House Harriers The Hash House Harriers (HHH or H3) is an international group of non-competitive running social clubs. An event organized by a club is known as a Hash or Run, or a Hash Run. A common denominal verb for this activity is Hashing, with participan ...

, a social running club based in

Houston Houston (; ) is the most populous city in Texas, the most populous city in the Southern United States, the fourth-most populous city in the United States, and the sixth-most populous city in North America, with a population of 2,304,580 ...

, Texas