Fortnite is an online game developed by Epic Games in the form of different game modes that share the same general gameplay and game engine. The game modes include: Fortnite: Save the World, a cooperative shooting and fighting game survival designed for up to four players and whose goal is to fight zombies and defend objects using fortifications, and Fortnite Battle Royale, a free-to-play battle royale game where up to 100 players fight among themselves until the last survivor. These two game modes are not recommended for those under the age of twelve in Europe (PEGI: 12) and for those under the age of thirteen in North America (ESRB: Adolescents).

The Fortnite: Save the World game mode was released in early access from July 2017, while the Fortnite Battle Royale mode was released from September 2017 in early access; Save the World is available only for Microsoft Windows, macOS, PlayStation 4, Xbox One, PlayStation 5 and Xbox Series, while Battle Royale has been released for the latter platforms, but also for Nintendo Switch and iOS and Android devices.

While both games were a success for Epic Games, Fortnite Battle Royale became a social phenomenon, attracting more than 125 million players in less than a year and generating hundreds of millions of dollars per month. Epic Games announced in 2019 that Fortnite had 250 million players, twice as many as in June 2018.

On March 22, 2023, following a live conference, Epic Games claims more than 500 million registered players.