Schooling in Spain is state-funded and compulsory between the ages of three and sixteen. However, parents or legal guardians must pay for books, materials, and sometimes uniforms for their children. Generally speaking, there are three categories of Spanish schools in the Spanish education system: public schools (colegios públicos), which are mostly state-funded; private schools (colegios privados), which are privately funded; and semi-private schools (colegios concertados), which are funded partially by the state and partially by private sources.