Yiddish song is a general description of several genres of Jewish music sung in Yiddish which includes songs of Yiddish theatre, Klezmer songs, and "Yiddish art song" after the model of the German Lied and French mélodie.
From the fourteenth century secular songs were sung in Yiddish, though rabbis of the period directed that sacred songs were only to be sung in Hebrew.
One of the main genres of Yiddish folk song in Central and Eastern Europe is Klezmer, which was also exported to America and Israel, though Henry Sapoznik (2005) writes "Historically, Yiddish song and theater have had a higher visibility than klezmer music in Israel." Generally 17th and 18th century songs and lullabies are anonymous, but the composers of others such as are known; such as Oyfn Pripetshik "On The Hearth" by Mark Warshawsky.
In Europe many of the songs of the Yiddish theatre companies were composed as incidental music to musical theatre, or at least plays with strong musical content, whereas others are "hit" individual arias and numbers culled from Yiddish operetta. In America, aside from America's own Yiddish theatres, songwriters and composers employed Yiddish folk and theatre songs, along with synagogue modes and melodies, as material for the music of Tin Pan Alley, Broadway and Hollywood.Irving Berlin was one of the popular composers to move from Yiddish song to English songs.Bei Mir Bistu Shein is an example of a Yiddish song which was later recast as an English hit.
Di Shvue "The Oath" (1902) was the Yiddish anthem of the socialist, General Jewish Labour Bund in early 1900s Russia. Another song by the same composer, S. Ansky (Shloyme Zanvl Rappoport), was In Zaltsikn Yam "In the Salty Sea". Yiddish workers' choral societies continued - including that led by Lazar Weiner in New York until the 1960s. Zog Nit Keyn Mol "Never say (this is the end of the road)" was a partisan song written in 1943 by Hirsh Glick, for the Vilna Ghetto resistance.