H4
H4, H04, or H-4 may refer to:
Biology and medicine
ATC code H04 Pancreatic hormones, a subgroup of the Anatomical Therapeutic Chemical Classification System
Histamine H4 receptor, a human gene
Histone H4, a protein involved in the structure of chromatin in eukaryotic cells
Technology
H-4 SOW, a precision-guided glide bomb used by the Pakistan Air Force
Halo 4, a video game created by 343 Industries for the Xbox 360
Harrison Number Four, an 18th-century marine chronometer designed by John Harrison
Zoom H4 Handy Recorder, a handheld digital audio recorder
<h4></h4>, level 4 heading markup for HTML Web pages, see HTML element#heading
Transport
Automobiles and roads
H4, a halogen headlamp 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)
H4 Dansteed Way, a road in Milton Keynes, England
Aviation
Hughes H-4 Hercules (Spruce Goose), the largest flying boat ever built
H4, IATA code for Héli Sécurité Helicopter Airlines, based in France
