A Frontisterion (transliteration of the term in Katharevousa), or Frontistirio (transliteration of the term in Modern Greek), or Φροντιστήριο (Greek) is a prevalent type of private cram school in Greece.
Most Greek secondary education students whose families can afford the significant fees attend a frontistirio, because of the low quality of state-sponsored education in Greece. It is generally considered impossible for all but the most gifted students to pass university entrance exams without this extra help. An even more expensive alternative is to hire private teachers who tutor the students at home (usually one teacher per subject).
Nowadays, Frontistiria (transliteration of the plural form of the word) and private teachers who cater to university students are also becoming common.