Jan Pieterszoon Sweelinck (1562-1621) was a Dutch composer and organist, known for his significant contributions to early Baroque music. He spent most of his life in Amsterdam, where he served as the organist at the Oude Kerk. Sweelinck's music is characterized by intricate counterpoint and rich harmonies, influencing many composers in Europe. Sweelinck is particularly famous for his keyboard works, including variations and toccatas, as well as his choral compositions. His style blended Renaissance traditions with emerging Baroque elements, making him a pivotal figure in the transition between these two musical periods.