There are different ways to categorize the sects of Judaism, depending on the time period and location. In the ancient era, Josephus, an early Jewish historian of Judea, defined four major sects of Judaism: Pharisees, Sadducees, Essenes, and Zealots. The Pharisees were the most popular sect in Judea, and they believed in a combination of fate and free will and that the soul is indestructible. The Sadducees were another major sect in Israel during the two centuries prior to the destruction of the Second Temple in the year 70 C.E. They were involved in government, in community, and in religious practices. The Essenes were a Jewish religious sect that was stricter than the Pharisees in regards to the Sabbath, and they devoted much of their time to studying. The Zealots were a political movement that sought to overthrow Roman rule in Judea.

In modern times, there are several different branches or denominations of Judaism. In North America, the four main branches include Orthodox, Reform, Conservative, and Reconstructionist. Orthodox Judaism is considered the most traditional form of modern Judaism, and it views itself as the continuation of the beliefs and practices of normative Judaism. Conservative Judaism attempts to combine a positive attitude toward modern culture, acceptance of critical secular scholarship regarding Judaisms sacred texts, and commitment to Jewish observance. Reform Judaism emphasizes the evolving nature of the religion, and it seeks to adapt to modern society. Reconstructionist Judaism emphasizes the role of the Jewish community in shaping Jewish tradition and practice.

Its worth noting that the Jewish groups themselves reject characterization as sects, as the term "sect" traditionally refers to religious subgroups that have broken off from the main body, and this separation usually becomes irreparable over time. Within Judaism, individuals and families often switch affiliation, and individuals are free to marry one another, although the major denominations disagree on who is a Jew.