The way that each stage of education is described has changed over many years.
Key Stage 0: Nursery and reception years (3–5 years old), now included as part of the Early Years Foundation Stage.
Key Stage 1: Years 1 to 2 (5–7 years old)
Key Stage 2: Years 3 to 6 (7–11 years old)
Key Stage 3: Years 7 to 9 (11–14 years old)
Key Stage 4: Years 10 to 11 (14–16 years old).
The exams at the end of this stage are typically of the GCSE level.
Key Stage 5: Years 12 to 13 (16–18 years old), more commonly referred to as Sixth Form. The exams at the end are typically A-Levels, AS-Levels, NVQs or National Diplomas
See Qualification Table for a list of typical qualifications and their level.