Secular music is music that is not primarily concerned with religion and is not intended to be used in religious services. It is the opposite of sacred music.
Secular music and sacred music were the two main genres of Western music during the Middle Ages and Renaissance era. There are relatively few written records of secular music from the former period because it was written down much less frequently than was sacred music, in part because of the high cost of paper or parchment. Another reason was that secular musicians profited from performing their original songs and writing them down would facilitate their theft by other musicians.