A gaming service provided by Blizzard Entertainment and a desktop PC application under the same name, required to play Blizzard's PC games.
Battle.net was the first online gaming service incorporated directly into the games that make use of it, in contrast to the external interfaces used by the other online services at the time. This feature, along with ease of account creations and the absence of member fees, caused Battle.net to become popular among gamers and became a major selling point for Diablo and subsequent Blizzard games. Since the successful launch of Battle.net, many companies have published online game services mimicking Blizzard's service package and the user interface.
In 2016, just in time for the 20th anniversary Blizzard announced to drop battle.net as a name for their services, mainly because newer players often get confused by not knowing the origin of battle.net. The first step has been made in March 2017 by renaming the battle.net desktop client to Blizzard App.