They involve studying the theory of a subject, combined with some investigative work. Some subjects also involve practical work.
They're available in more than 40 academic and nine applied subjects. The applied subjects are related to a broad area of work, such as engineering or tourism, and many are double the size of traditional GCSEs.
Young people can also take many GCSEs as short courses - these are equivalent to half a full GCSE, so can be taken in half the time.
GCSEs are graded A*-G and U (unclassified).
GCSEs are at levels 1 and 2 on the National Qualifications Framework, depending on the grade achieved.
Completing GCSEs at level 1 means a young person could move on to other courses or work-based training at levels 1 or 2.
Getting a GCSE can lead to a young person progressing to work, further study or an apprenticeship.