From Destinypedia, the Destiny wiki
Dungeons are an endgame activity.
Dungeons are Raid-like activities that feature unique mechanics and bosses throughout. They are longer than Raid Lairs, but remain shorter than proper Raids, and can take up to a couple hours with a sufficiently coordinated fireteam. The first Dungeon, The Shattered Throne, debuted in Forsaken, while the Pit of Heresy was introduced with the Shadowkeep expansion. Prophecy debuted in Season of Arrivals.
List of Dungeons
List of appearances