The term "ultra-Orthodox", however, is considered pejorative by many of its adherents.
Haredi Judaism is a reaction to societal changes including emancipation, enlightenment, the Haskalah movement derived from enlightenment, acculturation, secularization, religious reform in all its forms from mild to extreme, the rise of the Jewish national movements, etc.
In contrast to Modern Orthodox Judaism, which hastened to embrace modernity, the approach of the Haredim was to maintain a steadfast adherence both to Jewish Law and custom by segregating themselves from modern society.
Haredi communities are primarily found in Israel, North America, and Western Europe.
Their estimated global population currently numbers 1.3–1.5 million, and, due to a virtual absence of interfaith marriage and a high birth rate, their numbers are growing rapidly.
Others, such as Samuel Heilman, criticized terms such as "ultra-Orthodox" and "traditional Orthodox", arguing that they misidentify Haredim as more authentically Orthodox than others, as opposed to adopting customs and practises that reflect their desire to separate from the outside world. In Israel, Haredi Jews are sometimes also called by the derogatory slang words dos (plural dosim), that mimics the traditional Ashkenazi Hebrew pronunciation of the Hebrew word datim, meaning religious, According to its adherents, the forebears of the contemporary Haredim were the traditionalists of Eastern Europe who fought against modernization.
In 1919, Yosef Chaim Sonnenfeld and Yitzchok Yerucham Diskin founded the Edah Ha Chareidis as part of Agudath Israel in then Mandate Palestine.Hungarian Jewry split into two major institutionally sectarian groups, Orthodox and Neolog.However, some communities refused to join either of the groups calling themselves Status Quo.In Germany, the opponents of Reform rallied to Samson Raphael Hirsch, who led a secession from German Jewish communal organizations to form a strictly Orthodox movement with its own network of synagogues and schools.His approach was to accept the tools of modern scholarship and apply them in defence of Orthodoxy.
Schick demonstrated support in 1877 for the separatist policies of Samson Raphael Hirsch in Germany.