Various branches of Judaism, as well as Jewish religious or secular communities and political movements around the world elect or appoint their governing bodies, often subdivided by country or region.
There were the heads of the original Hebrew tribes, and then also prophets such as Moses, Jeremiah and Samuel and whose words inspire people to this day, judges such as Samson, kings such as David and Solomon, priests of the Temple in Jerusalem, and the Sanhedrin which was the judiciary.
After the destruction of the Second Temple and the subsequent exile for almost two thousand years, the Jews scattered throughout the world turned to their most learned rabbis for local leadership and council.
During Bar Kokhba's revolt against Roman Empire (132-135), the supreme religious authority Rabbi Akiva sanctioned Simon bar Kokhba to be a war leader, whereas during the 2nd century Judah haNasi was not only the supreme temporal leader sanctioned by Rome, but also edited the original work of the Mishnah which became the "de facto constitution" of the world's Jewry.
The writings and rulings of those such as Rashi (1040–1105), Maimonides (1135–1204), Yosef Karo (1488–1575) who published the most widely accepted code of Jewish law the Shulkhan Arukh, Isaac Luria (1534–1572), the Vilna Gaon (1720–1797), the Chafetz Chaim (1838–1933) and many others have shaped Jewish law for almost two thousand years, as their religious rulings were published, distributed, studied, and observed until the present time.
The loose collection of learned rabbis that governed the dispersed Jewish community held sway for a long time.
In Western Europe, especially in monarchies, where no equal rights were granted for the Jewish population, radical Maskilim defined the new role of religion as an education of just citizens — like Moses Mendelssohn in his book Jerusalem or On Religious Power and Judaism which was a response to the Prussian reformer Christian Wilhelm von Dohm.
New leaders such as Israel Jacobson, father of the German Reform Judaism movement, launched an egalitarian, modernist stance that challenged the Orthodoxy.
"Rabbi" is not a universal term, however, as many Sephardic rabbinic Jewish communities refer to their leaders as Hakham ("wise man").
Every major American city has its local "Jewish Federation", and many have sophisticated community centers and provide services, mainly health care-related.
A Karaite synagogue is run by a board of directors, and its spiritual leader is often called a Hakham, the equivalent of a "rabbi", and matches one in function.