Bertsolaritza is the art of composing and singing songs extemporaneously in Basque according to rhyming patterns and melodies. A composed piece is called a bertso, and the singer is a bertsolari. Traditionally performed by men, more women are now participating as well. There are many famous bertsolaris in the Basque country, and bertsolari championships have been held since the 1930s, organized initially by youth groups and later an academy, with a unified championship forming in the 1980s held every four years.