The lyceum is a category of educational institution defined within the education system of many countries, mainly in Europe. The definition varies among countries; usually it is a type of secondary school. Basic science and some introduction to specific professions are generally taught.

A secondary school or high school is an institution that provides secondary education. Some secondary schools provide both lower secondary education and upper secondary education, i.e., both levels 2 and 3 of the ISCED scale, but these can also be provided in separate schools.