Preschool education is organized in different cycles and serves the 2–4 age group and the 4–6 age group. Preschool education is not mandatory except for the last year. Basic education is compulsory and serves the population of the 6–14 age group. Secondary education is not compulsory, although it is the duty of the state to offer it for free. It caters to the 14–18 age group and is organized in a common core of four years and three modes of two years of study that are offered in three different options: general or academic, vocational (industrial, agricultural, and services), and artistic.