Secondary school or High School is the name used for the last segment of compulsory education. In England, Wales and Northern Ireland the term "high school" is not used generically, despite the fact that some such schools use the words 'High School' in their name.

In UK students transfer from primary school to secondary school at age 11. Education is compulsory to age 16 and schooling continues for 2 further years after that. Traditionally the five years of compulsory secondary schooling from ages 11 to 16 were known as "first year" through to "fifth year," but they have now been renamed Year 7 through to Year 11 (Year 8 to Year 12 in Northern Ireland). After Year 11 a student can opt to remain at school, to transfer to a college, or to leave education and seek work. Those who stay at school enter Years 12 and 13 (Years 13 and 14 in Northern Ireland). These years are traditionally known as the Sixth Form ("Lower Sixth" and "Upper Sixth"), and required students to specialise in three or four subjects for their A Levels. This is an unusually specialised curriculum for this age group by international standards, and recently some moves have been made to increase the number of subjects studied. There are also vocational qualifications aimed at this age group. After attaining the relevant A Level qualifications the student can enter university.