Abeir-Toril (or commonly referred to as Toril) is the name of the fictional planet that makes up the Forgotten Realms Dungeons & Dragons campaign setting, as well as the Al-Qadim and Maztica campaign settings and the 1st edition version of the Oriental Adventures campaign setting.
The name is archaic, meaning "cradle of life." It consists of various continents and islands, including Faerûn, Kara-Tur, Zakhara, Maztica, Osse, Anchorome and Katashaka, a sub-Saharan-like continent south of Maztica, where humanity appeared. Toril was originally the name of Jeff Grubb's personal campaign world before it was merged with Ed Greenwood's Forgotten Realms setting.
Toril was the name of Jeff Grubb's campaign world, and it was adopted as the name of the planet upon which the continent of Faerûn existed when he and Ed Greenwood were designing the original Forgotten Realms Boxed Set in 1987. Abeir- was added as a prefix to the planet's name so that it would be the first entry in the alphabetical encyclopedia of terms included in the set. The setting's entire planet underwent a major change during the 1989 Avatar trilogy, which detailed a series of events called the Time of Troubles, during which gods walked the earth and magic became unpredictable. These events caused permanent changes in gameplay that were outlined in the Advanced Dungeons & Dragons 2nd edition campaign setting books.