The independent schools trade body, the Independent Schools Information Service, prefers to define public schools as a long-established, student-selective, fee-charging independent secondary school that caters primarily for children aged between 11 or 13 and 18, and whose head teacher is a member of the Headmasters' and Headmistresses' Conference (HMC).[3] The 'public' name refers to the schools' origins as schools open to any public citizen who could afford to pay the fees; they are not funded from public taxes. It is usually applied to describe the 215 independent (and mainly boys') secondary schools belonging to the HMC, although it can also be used to describe the 230 girls' senior schools belonging to the Girls' Schools Association.[3]