A cockfight is a blood sport, held in a ring called a cockpit. The first documented use of the word gamecock, denoting use of the cock as to a "game", a sport, pastime or entertainment, was recorded in 1634, after the term "cock of the game" used by George Wilson, in the earliest known book on the sport of cockfighting in The Commendation of Cocks and Cock Fighting in 1607. But it was during Magellan's voyage of discovery of the Philippines in 1521 when modern cockfighting was first witnessed and documented for Westerners by the Italian Antonio Pigafetta, Magellan's chronicler, in the Kingdom of Taytay.

The combatants, referred to as gamecocks (not to be confused with game birds), are specially bred and conditioned for increased stamina and strength. Male and female chickens of such a breed are referred to as game fowl. Cocks possess congenital aggression toward all males of the same species. Wagers are often made on the outcome of the match.

Cockfighting is a blood sport due in some part to the physical trauma the cocks inflict on each other, which is sometimes increased by attaching metal spurs to the cocks' natural spurs. While not all fights are to the death, the cocks may endure significant physical trauma. In some areas around the world, cockfighting is still practiced as a mainstream event; in some countries it is regulated by law, or forbidden outright. Advocates of the "age old sport" often list cultural and religious relevance as reasons for perpetuation of cockfighting as a sport.