In most contemporary educational systems of the world, secondary education comprises the formal education that occurs during adolescence. It is characterized by transition from the typically compulsory, comprehensive primary education for minors, to the optional, selective tertiary, "postsecondary", or "higher" education (e.g. university, vocational school) for adults.
Depending on the system, schools for this period, or a part of it, may be called secondary or high schools, middle schools, colleges, or vocational schools. secondary education also varies from country to country and even within them but is generally around the seventh to the tenth year of schooling. Secondary education occurs mainly during the teenage years.