AS-levels are advanced qualifications typically taken by students in the United Kingdom during their first year of sixth form, usually at age 16 to 17. They are part of the A-level system and serve as a foundation for further study. Students usually take three to four subjects, which can include a mix of sciences, humanities, and arts. The results from AS-levels can contribute to a student's overall A-level grade if they choose to continue studying those subjects in the second year. These qualifications are recognized by universities and can influence admission decisions.