C4

C4, C04, C.IV, C-4, or C-04 may refer to:

Places

 * Caldwell 4 or NGC 7023 or Iris Nebula, a reflection nebula in the constellation Cepheus
 * Circumferential Road 4 or C-4, an arterial road of Manila, Philippines
 * Ken-Ō Expressway, a road in Japan (includes some sections of Shin-Shōnan Bypass)
 * Omotesandō Station, a Tokyo Metro subway station (station number: C-04)

People

 * C4 (rapper), a rap music producer from Birmingham, England
 * Clarence Mitchell IV, American radio host and former politician
 * Chris Turner, sometimes credited as Chris Heiner, a.k.a. "C4", Australian musician, part of Modern Day Poets

Computing

 * C4 (conference), a Macintosh software developers conference
 * C4 Engine, a next-generation 3D game engine
 * C4 model (software), a graphical notation technique for diagramming software architecture
 * Cx4 chip, an add-on microprocessor chip employed by certain Super NES game cartridges (often incorrectly referred to as the C4 chip)
 * Controlled collapse chip connection or flip chip, a method for interconnecting semiconductor devices
 * VIA C4, a planned design of central processing unit for a personal computer

Music

 * C4 (American band), a neo-classical metal band set up by Michael Angelo Batio
 * C4 (French band), French boyband
 * C4 (mixtape), mixtape by American rapper Kendrick Lamar
 * C4, scientific pitch notation for the note "Middle C" (261.626 Hz)
 * C4 Records, a record label
 * Tha Carter IV, album by American rapper Lil Wayne

Other uses in arts, entertainment and media

 * C4 (New Zealand TV channel), a former New Zealand television music channel
 * 1. c4, also called the English Opening, a chess opening
 * The abbreviation for British TV channel Channel 4.

Biology

 * C4: an EEG electrode site according to the 10-20 system
 * Apolipoprotein C4, a protein encoded by the APOC4 gene
 * c4 antisense RNA, a non-coding RNA
 * ATC code C04 Peripheral vasodilators, a subgroup of the Anatomical Therapeutic Chemical Classification System
 * C4 carbon fixation, a pathway for carbon fixation in photosynthesis that produces C4 plants
 * Cervical spinal nerve 4, a nerve originating in the neck
 * Cervical vertebra 4, one of the cervical vertebrae of the vertebral column
 * C04, oral cancer ICD-10 code
 * Complement component 4, a protein involved in the intricate complement system, encoded by C4A or C4B gene in humans
 * C4 fragments, one of the types of products of catabolism pathways

Mathematics

 * $$C_4$$, the cyclic group of order 4
 * C4, the fourth pure "core" module in the Edexcel A-level mathematics examination

Other uses in science and technology

 * C4, butyl-type hydrocarbon chain, a type of four-carbon molecule, especially in C4 reversed-phase chromatography columns
 * Cluster 4, an ESA satellite that studies the Earth's magnetosphere over the course of an entire solar cycle

Organizations

 * C4 (Colombia), a political party in Colombia
 * C4, a social welfare non-profit entity organized under section 501(c)(4) of the U.S. Internal Revenue Code
 * Churches Covered and Connected in Covenant, a religious association founded by Archbishop LeRoy Bailey Jr.
 * Craiova Group, a cooperation project of four European states

Sports

 * C4 (classification), a Paralympic cycling classification
 * C-4, professional wrestler Paul Burchill's name for his finishing move, a moonsault uranage
 * C4, an abbreviation for a four-man Sprint Canoe, see Canoe racing
 * C4, a term used to refer to the UEFA Intertoto Cup, a football competition (mainly used in non-English speaking countries)
 * C4 level, a challenge square dance program at the Challenge 4 level

Stationery

 * C4, an international standard paper size (229 × 324 mm), defined in ISO 216
 * C4, the envelope size matching the A4 paper size

Aircraft

 * C-4, the US Army designation of the Ford Trimotor
 * AEG C.IV, a German World War I reconnaissance aircraft
 * AGO C.IV, a 1917 German reconnaissance aircraft
 * C-4 Academe, the military version of Gulfstream I twin turboprop business aircraft
 * C-4 Argonaut, a Canadair aircraft derived from the Douglas DC-4
 * Cierva C.4, a 1922 Spanish experimental autogyro
 * DFW C.IV, a 1916 German reconnaissance aircraft
 * Flight Design C4, a four-seat light aircraft
 * Fokker C.IV, a 1923 Dutch two-seat reconnaissance aircraft
 * Rumpler C.IV, a 1917 German single-engine, two-seater reconnaissance biplane

Automobiles

 * C4, a class of Audi 100 and Audi A6 cars
 * Chevrolet Corvette C4, the fourth production design of the Chevrolet Corvette
 * Citroën C4, a car made by Citroën
 * Coloni C4, a Formula One car built by Enzo Coloni Racing Car Systems
 * Sauber C4, a Sauber sportscar
 * Spyker C4, a Spyker car

Locomotives

 * Bavarian C IV, an 1884 German steam locomotive
 * GS&WR Class C4, a Great Southern and Western Railway Irish steam locomotive
 * LNER Class C4, a class of British steam locomotives

Ships

 * HMS C4, a British C class submarine of the Royal Navy
 * Type C4 ship, merchant cargo ships of United States Maritime Commission "C" design
 * USS C-4 (SS-15), a United States C class submarine of the United States Navy
 * USS Philadelphia (C-4), a protected cruiser of the United States Navy

Vehicle components

 * Ford C4 transmission, an automatic transmission
 * Menasco C4, a 1930s 4-cylinder, air-cooled, in-line, inverted, aero-engine

Weapons

 * C-4 (explosive), a type of plastic explosive
 * Hafdasa C-4, an Argentine submachine gun

Other uses

 * C4, a variation of Command and control, meaning "Command, Control, Communications and Computers"
 * C4, the monogram of Christian IV of Denmark, used in the city arms of Kristianstad, Sweden since 1622
 * C4 Extreme, a sports nutrition supplement product line by Cellucor, which includes C4 energy drinks.