Béla Bartók's Mikrokosmos series contains 153 progressive piano pieces published across six volumes by Editio Musica Budapest. The series, which was written between 1926 and 1939, starts with very easy beginner etudes and progresses to difficult advanced technical displays, and remains an essential part of modern piano lessons and education.
The word Mikrokosmos may be interpreted as a series of pieces in many different styles, representing a small world. Or it may be interpreted as world of the little ones, the children.