Haredi Judaism consists of groups within Orthodox Judaism that are characterized by their strict interpretation of religious sources and their accepted halakha and traditions, in opposition to more accommodating or modern values and practices. Its members are usually referred to as ultra-Orthodox in English; however, the term "ultra-Orthodox" is considered pejorative by many of its adherents, who prefer terms like strictly Orthodox or Haredi. Haredi Jews regard themselves as the most religiously authentic group of Jews, although other movements of Judaism disagree.

Orthodox Judaism is the collective term for the traditionalist branches of contemporary Judaism. Theologically, it is chiefly defined by regarding the Torah, both Written and Oral, as revealed by God to Moses on Mount Sinai and faithfully transmitted ever since.