A secondary school (or a high school) describes an institution that provides secondary education and also usually includes the building where this takes place. Some secondary schools provide both lower secondary education (ages 11 to 14) and upper secondary education (ages 14 to 18), i.e., both levels 2 and 3 of the ISCED scale, but these can also be provided in separate schools.
In the US, the secondary education system has separate middle schools and high schools. In the UK, most state schools and privately-funded schools accommodate pupils between the ages of 11–16 or 11–18; some UK private schools, i.e. public schools, admit pupils between the ages of 13 and 18.
Secondary schools follow on from primary schools and prepare for vocational or tertiary education. Attendance is usually compulsory for students until age 16. The organisations, buildings, and terminology are more or less unique in each country.