Yiddish was a widely spoken everyday language in central and eastern Europe in the first half of the 20th century, but the number of speakers declined dramatically after the Holocaust. For many Jews nowadays Yiddish represents the language of memory and identity, and is part of a wider Jewish culture.
An article of the New Internationalist website looks at the origin of Yiddish, and has clips from people whose jobs involve promoting the language. Yiddish these days is thriving in Stamford Hill, Brooklyn, among other places, according to the article.
Here's the article.