The Greek education system consists of three levels: primary, secondary, and tertiary. Primary education is for ages 6-15 and is compulsory. It takes place in primary schools and lasts for six years. Secondary education has two stages - compulsory lower secondary and post-compulsory upper secondary, which can take place in unified lyceums or technical/vocational schools lasting two to three years. Tertiary education occurs at universities, technological institutes, or open universities, and typically lasts eight to twelve semesters.