Bartók’s music has many modern techniques such atonality, bitonality and modern harmonies. He often uses different kinds of scales (not just major and minor ones), and very complicated rhythms. A lot of these are inspired by the folk music he heard. He wrote a lot of piano music, including some easy pieces for people who are learning the piano. This includes a collection of pieces in six volumes called "Mikrokosmos" which are very popular with young musicians today.