From New Music USA:
There is a saying that a language is a dialect with an army and a navy. Yiddish, the historic language of Central and East European Jewry, never had either and suffered miscategorization as a jargon and corruption of German. On the contrary, Yiddish is an extraordinarily rich language with a remarkable literary and folk culture. It is a fusion of medieval Germanic dialects with Hebrew and Aramaic, and components drawn from other language families as well. It is written with the Hebrew Alphabet (from right to left), has its own grammar, and a variety of regional dialects.