What parts of rockets become space junk?

Space junk, or space debris, primarily includes used rocket stages, spent fuel tanks, and defunct satellites. When rockets launch, their various components, like boosters and fairings, often detach and can remain in orbit or re-enter the atmosphere. Additionally, fragments from collisions or disintegration of spacecraft also contribute to the growing problem of space debris. This junk poses risks to operational satellites and manned missions in space.