The A Level (Advanced Level) is a subject-based qualification conferred as part of the General Certificate of Education, as well as a school leaving qualification offered by the educational bodies in the United Kingdom and the educational authorities of British Crown dependencies to students completing secondary or pre-university education. A number of countries, including Singapore, Kenya, Mauritius and Zimbabwe have developed qualifications with the same name as and a similar format to the British A Levels. Obtaining A Level or equivalent qualifications is generally required for university entrance, with universities granting conditional offers based on grades achieved.

Normally, students take between 3-5 A Levels in their first year of sixth form, with the majority deciding to drop down to 3 for their second year. This is due to the fact that university offers are normally based on 3 A Levels. Unlike other level 3 qualifications such as the International Baccalaureate, A Levels have no specific requirements for which subjects to study, so students have the opportunity to combine any subjects they wish to take. However, students normally pick their courses based on the degree they wish to pursue at university: most degrees require specific A Levels for entry, such as A Level Mathematics for a Mathematics degree.

A Levels are generally worked towards over two years. Between 2015 and 2018 (first assessment Summer 2017), new style linear A Levels are being introduced in England as part of the government’s educational reforms (initially across 13 subjects), replacing older modular courses where exams could be taken at several points during the course. Instead, reformed A Levels are now taken as a set of terminal exams, and are no longer separated into units. There is less emphasis on coursework, and students must resit all exams if they wish to resit the qualification. Additionally, the AS Level is now a separate qualification and is not required for an A Level award, although still encompasses the first year of the full A Level content. However, as these reforms won’t be complete until 2018, students still sit AS Level exams as part of an A Level in unreformed qualifications, most notably Mathematics which is not reformed until 2017. Hence some students may be taking a combination of modular and linear courses during this transition period. Controversially, various A Level courses have been abolished from 2017 as part of these reforms, including Archaeology, Creative Writing and Home Economics among others.

In the older modular courses, A Levels are split into two parts, with first known as the Advanced Subsidiary Level, commonly referred to as the AS Level, which serves as a qualification in its own right aiding university admission, and the second part is known as the A2 Level, which is more in-depth and academically rigorous than the AS Level. The AS Level combines with the A2 Level combined for a full A Level award. The A2 Level is not a qualification on its own, and must be accompanied with an AS Level in the same subject for certification.