In Harry Potter and the Order of the Phoenix, what is the name of the student group Harry teaches?

In Harry Potter and the Order of the Phoenix, Harry teaches a student group called Dumbledore’s Army.

The group forms because the Ministry of Magic appoints Dolores Umbridge as Hogwarts’ Defence Against the Dark Arts teacher. Her lessons emphasize theory and restrict practical spellwork, even though students are worried about Lord Voldemort’s return. Hermione suggests that Harry teach them defensive magic himself.

The students meet secretly in the Room of Requirement, a magical room that appears when people need it. Harry teaches spells including the Shield Charm and the Patronus Charm. The members use the name Dumbledore’s Army partly as a joke and partly to suggest that Albus Dumbledore is organizing resistance against the Ministry.

The name is sometimes confused with the Order of the Phoenix, the adult organization fighting Voldemort. Dumbledore’s Army is a separate student group. The film’s final confrontation at the Department of Mysteries demonstrates how much the students have learned, although the group’s secrecy is eventually exposed.