Wizards of the Coast (WotC) is a publisher of roleplaying games and collectible card games, most notably Dungeons & Dragons and Magic: The Gathering, respectively. Wizards purchased TSR, Inc. (the original publisher of Dungeons & Dragons) in 1997, and was in turn purchased by Hasbro in 1999.
Before it became world-famous as the publisher of Magic: The Gathering, Wizards of the Coast was first a developer and publisher of roleplaying games. Jonathan Tweet and Lisa Stevens saw their careers in games development take off at White Wolf (or rather, at the Wolf's predecessor Lion Rampant) prior to working at Wizards, and as a result the two companies had a good working relationship in the mid-1990s.
During this time, Wizards had several deals to publish games using White Wolf's intellectual properties. In 1994, Wizards developed Jyhad (later Vampire: The Eternal Struggle), a collectible card game based on Vampire: The Masquerade and designed by Richard Garfield, the creator of Magic: The Gathering. Wizards also published two other, less successful CCGs based on White Wolf properties: Rage (based on Werewolf: The Apocalypse), and Arcadia (based on Changeling: The Dreaming). Publication on all three games ceased publication in 1996, and ownership reverted to White Wolf. While White Wolf resumed production of new sets for V:TES from 2000 to 2010, Rage saw several successive ill-fated revivals with third-party licensors, and Arcadia remained cancelled outright.
Wizards also bought the roleplaying game Ars Magica from White Wolf in 1994, and began work on a fourth edition of the game. Wizards published only four supplements for the game: the first, the Medieval Handbook, was developed by White Wolf for Third Edition prior to the sale and was ultimately published by Wizards, and the other three (Faeries: Revised Edition, Houses of Hermes, and Lion of the North: The Loch Leglan Tribunal) were developed by Wizards in-house. Before the Fourth Edition rulebook finished development, Wizards killed off their roleplaying games division and sold the rights to Ars Magica to Atlas Games in 1994, having owned and published the game for less than a year. Atlas completed and published Ars Magica Fourth Edition, and continues to publish new books for Ars Magica (now into its Fifth Edition) to this day.
Ironically enough, it was only three years after Wizards shut down their internal roleplaying games department that they bought the bankrupt games publisher TSR and, in doing so, enabled roleplaying games like Dungeons & Dragons to stay in active development and publication. Shortly after Wizards bought TSR, they began developing a new third edition of D&D in earnest. This new edition saw print in 2000, and at the core of the game was the new d20 System, which was co-developed by Jonathan Tweet, Monte Cook and Skip Williams. The Open Game License allowed other publishers to use the d20 System (with some restrictions) at no cost. From 2000 to 2006, White Wolf published a number of books using the d20 System under the OGL through the Sword & Sorcery and/or Arthaus imprints. In addition to original content made by White Wolf (via Sword & Sorcery Studios) or published on behalf of other developers (such as Monte Cook's Malhavoc Press), this imprint also published licensed material based on Wizards' Ravenloft and Gamma World settings.