In Hong Kong, prom culture is inherited from the western countries and is generally called a ball, such as Christmas Ball. This usually takes place during Christmas and summer break. This is more popular in the secondary education stage rather than in universities. Schools, apart from international schools, holding proms are usually single-sex schools where normally the student unions in the schools will cooperate with each other in organizing the event. In recent years, more and more individual unions got united and formed different student unions associations so as to organize large-scale events including large joint-school proms. Except for those proms within the academic field, there are also adult proms for charity yearly where celebrities and government officers always go to these functions.