The General Certificate of Secondary Education (GCSE) is the name of a set of British examinations, usually taken by secondary school students at age 15–16 in England, Wales and Northern Ireland (but not Scotland, where the equivalent is called Standard Grade).

A different examination is taken for each area of study, but school students are usually obliged to take examinations for certain "core subjects" (English language, English literature, mathematics, and science) along with several optional subjects; sometimes up to 10–14 in total. There is also an option for students to take "short" or "half" courses for certain subjects.

There are different tiers for most examination — normally 'foundation' (formerly 'Basic') and 'higher', and for mathematics, 'intermediate'. Students are entered for a certain tier based on their ability. The tier a student is entered for affects the range of grades that student could attain.

Grades range from an A* (A-star) to G, with a U as a fail. The A* was introduced in 1994 due to the increasing number of students attaining A-grades. Originally, to get an A* a student had to take an extra paper; the system was then revised to make the higher paper take this into account.

Some subjects, such as science, can be split up into several different subjects: it is possible to be examined on science as a whole, or biology, chemistry and/or physics separately.

Some examining boards offer a "modular" structure for some subjects, alongside the more traditional "linear" structure. In a modular structure, one or more modular examinations which focus on a sub-set of the syllabus are taken at intermediate stages of the course. Modular examinations may be re-taken to attempt to improve results. In addition to modular examinations, a modular structure may also include final or terminal examinations which examine the whole syllabus.

In most subjects, one or more coursework assignments may also be completed. Coursework typically contributes around 25% to the final GCSE grade. Although in subjects such as DT (design and technology - woodwork, metalwork electronics etc) and IT (information technology - work on computers) the amount of mark relying on coursework is greater.

GCSE was introduced for teaching in September 1986, and replaced both the O-level GCE (Ordinary level General Certificate of Education) and the CSE (Certificate of Secondary Education ) qualifications, which suffered problems due to the two-tieredness of the system.

Some commentators feel that the GCSE system is a dumbing down from the old GCE / O Level system, joking that it stands for Get Crampin Sylvia Examined or General Certificate for Sitting an Exam. Some public schools have even gone as far as removing GCSEs from their curricula and instead encourage their pupils to progress straight to A-level or the International Baccalaureate studies.

Introduced in 2000 was the Vocational GCSE, which encouraged students to take the work-related route and included courses such as applied business, ICT and leisure and tourism. From September 2004, the word Vocational will be dropped and a Vocational GCSE will be known simply as a GCSE. This is to show that the vocational side is 'on par' with the traditional academic side.