Jewish religious movements, sometimes called "denominations", include diverse groups within Judaism which have developed among Jews from ancient times. Today in the west, the most prominent divisions are between traditionalist Orthodox movements and modernist movements such as Reform Judaism originating in late 18th century Europe, Conservative originating in 19th century Europe, and other smaller ones, including the Reconstructionst and Renewal movements which emerged later in the 20th century in the United States.

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.