Klezmer (from Yiddish כּלי־זמיר, kley - instrument and zemer - song; etymologically from Hebrew k'li zemer כלי זמר, "musical instrument") is a musical tradition which parallels Hasidic and Ashkenazic Judaism. Around the 15th century, a tradition of secular (non-liturgical) Jewish music was developed by musicians called klezmorim or kleyzmurim. They draw on devotional traditions extending back into Biblical times, and their musical legacy of klezmer continues to evolve today. The repertoire is largely dance songs for weddings and other celebrations. Due to the Ashkenazi lineage of this music, the lyrics, terminology and song titles are typically in Yiddish.
Originally, klezmer (plural klezmorim) referred to musical instruments, and was later extended to refer to musicians themselves. It was not until the mid-to-late 20th Century that the word was used to identify a musical genre. Early 20th Century recordings and writings most often refer to the style as "Yiddish" music, although it is also sometimes called Freilech music. Compared to most other European folk music styles, very little is known about the history of klezmer music, and much of what is said about it must be seen as conjecture. .