Yiddish is a language that grew up among Jewish people in central and eastern Europe. Most of it is built on old German, so a German speaker can catch quite a lot of it, but it is written in Hebrew letters and holds many words from Hebrew and from Slavic languages such as Polish and Russian. Before the Second World War millions spoke it every day; the Holocaust killed most of those speakers, and today it is mainly kept alive by older people, by scholars, and by strictly religious Jewish communities in places like New York and Israel, where children still grow up speaking it. It is also used as a describing word: Yiddish literature, a Yiddish theatre, Yiddish songs. English itself has quietly borrowed a lot from Yiddish through New York, so words you may already know — bagel, klutz, schmuck, glitch, chutzpah, "I should worry" patterns of sentence — come from it. Two things worth keeping straight. Yiddish is not Hebrew: Hebrew is the ancient language of the Bible and the everyday language of Israel today, and the two are not related in family, only in alphabet and in shared words. And Yiddish is not slang or "broken German", though people used to call it that unkindly; it is a full language with its own grammar, newspapers and Nobel-prize-winning writers.