Judaism
Around the 1st century CE, there were several small Jewish sects: the Pharisees, Sadducees, Zealots, Essenes, and Christians. After the destruction of the Second Temple in 70 CE, these sects vanished. Christianity survived, but by breaking with Judaism and becoming a separate religion; the Pharisees survived but in the form of Rabbinic Judaism (today, known simply as "Judaism"). The Sadducees rejected the divine inspiration of the Prophets and the Writings, relying only on the Torah as divinely inspired. Consequently, a number of other core tenets of the Pharisees' belief system (which became the basis for modern Judaism), were also dismissed by the Sadducees. (The Samaritans practiced a similar religion, which is traditionally considered separate from Judaism.)
Judaism
Like the Sadducees who relied only on the Torah, some Jews in the 8th and 9th centuries rejected the authority and divine inspiration of the oral law as recorded in the Mishnah (and developed by later rabbis in the two Talmuds), relying instead only upon the Tanakh. These included the Isunians, the Yudganites, the Malikites, and others. They soon developed oral traditions of their own, which differed from the rabbinic traditions, and eventually formed the Karaite sect. Karaites exist in small numbers today, mostly living in Israel. Rabbinical and Karaite Jews each hold that the others are Jews, but that the other faith is erroneous.