>A Jewish friend once said to me that Hebrew is a formal language and Yiddish is a street language. Agree or disagree?

It certainly was true. Jews didn't want to use the "holy language" for everyday commerce, so developed alternatives--in the ancient world, they used Aramaic. More recently, we had Yiddish (a mix of Hebrew and German) for those in Eastern Europe, Ladino (a mix of Hebrew and Spanish) for those in Spain and other spanish-influenced areas.

Modern Hebrew is very much the child of Eliezer Ben-Yehuda, who systematized and modernized the language.

Tamar