The Haredi dialect is a vernacular spoken by Haredi communities in Israel. It evolved from "standard" pre-World War II varieties of Yiddish under the impact of the modern Hebrew, in particular of its phonology and lexicon. A great variability is observed in syntax, morphology, phonology, as well as lexicon among the Haredi communities. Their vernacular is preserved and evolved due to their unique conservative isolated way of life, with separate educational and public institutions. Most communities permit code switching between Haredi dialect and Hebrew, while some anti-Zionist Haredim reject Israeli Hebrew altogether.