Hearthstone is a free-to-play online digital collectible card game developed and published by Blizzard Entertainment. Originally subtitled Heroes of Warcraft, Hearthstone builds upon the existing lore of the Warcraft series by using the same elements, characters, and relics. It was first released for Windows and macOS in March 2014, with ports for iOS and Android released later that year. The game features cross-platform play, allowing players on any supported device to compete with one another, restricted only by geographical region account limits.

A digital collectible card game (DCCG) or online collectible card game (OCCG) is a computer or video game that emulates collectible card games (CCG) and is typically played online or occasionally as a standalone video game. Many DCCGs are types of digital tabletop games and follow traditional card game-style rules, while some DCCGs use alternatives for cards and gameboards, such as icons, dice and avatars. Originally, DCCGs started out as replications of a CCG's physical counterpart, but many DCCGs have foregone a physical version and exclusively release as a video game, such as with Hearthstone.