Which Harry Potter novel introduced the Triwizard Tournament?

Harry Potter and the Goblet of Fire introduced the Triwizard Tournament.

Published in 2000, the fourth Harry Potter novel brings Hogwarts into an international magical competition involving three schools: Hogwarts, Beauxbatons, and Durmstrang. Students selected as champions must complete three dangerous tasks, although Harry is unexpectedly entered despite being below the usual age requirement.

The tournament gives the novel a different structure from the earlier school-year stories, with long intervals between set pieces and a stronger international setting. Its final task leads Harry and Cedric Diggory to a graveyard, where Voldemort returns to physical form and the series takes a darker turn.

The Triwizard Tournament should not be confused with the Quidditch World Cup, which also appears near the beginning of the same book. The tournament is a separate magical contest involving champions from the three schools.