Dota 2 is a multiplayer online battle arena game developed by Valve Corporation. It's a stand-alone sequel to the WarCraft III custom map Defense of the Ancients: All-Stars (DotA). Development of Dota 2 began in 2009, when the developer of the DotA mod, IceFrog, was hired by Valve as lead designer. Dota 2 was released as a free-to-play title.
The International is Valve's annual tournament for Dota 2, where the best Dota 2 players compete for a crowd-funded, multi-million dollar prize pool.