Music has evolved over six periods throughout history. The earliest period was Medieval (500-1400) where monophonic Gregorian chant dominated and polyphony began to develop. The Renaissance (1400-1600) saw the introduction of instrumental music and the development of notation. In Baroque (1600-1760), composers experimented with form and instruments like the violin and opera emerged. Classical (1730-1820) was characterized by clearer structure and melodies like sonatas. Romantic (1815-1910) featured programmatic music and self-expression. The 20th century (1900-2000) brought new technologies and genres like rock and roll and hip hop that expanded how music was created and enjoyed.