The wizarding prison in J.K. Rowling’s Harry Potter books is Azkaban.
Azkaban is a prison for witches and wizards convicted of serious crimes under the authority of the British Ministry of Magic. It is located on an island in the North Sea and is guarded by Dementors for much of the series. The prison is first mentioned in Harry Potter and the Philosopher’s Stone and becomes especially important in later books.
The Dementors’ presence makes Azkaban one of the most feared places in the wizarding world. Their ability to drain happiness and feed on positive memories explains why prisoners can suffer severe psychological damage there. Sirius Black’s escape from Azkaban is a major event in Harry Potter and the Prisoner of Azkaban.
Azkaban is not the same as Nurmengard, another wizarding prison associated with the dark wizard Gellert Grindelwald. Gringotts is a wizarding bank, while Durmstrang is a European magical school.