X-Men is closely related to the existence of mutants on earth. In the Marvel world, mutant is a term aimed at humans with more abilities beyond normal limits. This ability is obtained from genetic mutations in the body. This excess is usually seen as a teenager.
Interestingly, mutants in the Marvel world are not only a few people, but rather numerous and divided into two big groups. First, mutants with the aim of wanting to dominate the human world and make ordinary people under their leadership. This group of mutants consider themselves far superior to ordinary humans and deserve to enslave them. This group is led by, among others, Magneto, with the Brotherhood of Mutants and Apocalypse with its ancient mutant army.
Second, mutants which aim to maintain the safety of mutants from threats posed by both humans and fellow mutants. On the other hand, they are trying to fight for the formation of a peaceful world where ordinary people and mutants can coexist. The biggest group from this line is X-Men.