The Elder Scrolls Online, abbreviated ESO, is a massively multiplayer online role-playing game (MMORPG) developed by ZeniMax Online Studios and published by Bethesda Softworks. It was released for Windows and macOS in April 2014. It is a part of the Elder Scrolls series. The game is set in the continent of Tamriel and features a storyline indirectly connected with the other games in the Elder Scrolls franchise. It had been in development for seven years before its release in 2014, with a mandatory monthly subscription model. It initially received mixed reviews. Reception improved significantly with the March 2015 re-release and rebranding as The Elder Scrolls Online: Tamriel Unlimited, transitioning to a buy-to-play model with microtransactions and an optional subscription. It was released for the PlayStation 4 and Xbox One consoles in June 2015, and for PlayStation 5 and Xbox Series X/S in June 2021. More than 18 million copies were sold by 2021, having around 2.5 million monthly active players in 2017.