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.)
Orthodox Judaism
In the State of Israel, where the total Jewish population is about 6.5 million, 22% of all Jewish respondents to a 2016 PEW survey declared themselves as observant Orthodox (9% "Haredim", or "Ultra-Orthodox", 13% "Datiim", "religious"). 29% described themselves as "traditional", a label largely implying little observance, but identification with Orthodoxy. The second largest Orthodox concentration is in the United States, where a 2013 PEW survey found that 10% of respondents identify as such, in a total Jewish population of at least 5.5 million. 3% were Modern Orthodox, 6% were Ultra-Orthodox, and 1% were "other" (Sephardic, liberal Orthodox, etc.) In Britain, of 79,597 households with at least one Jewish member that held synagogue membership in 2016, 66% affiliated with Orthodox synagogues: 53% in "centrist Orthodox", where congregants are often lax in observance, and 13% in "strictly Orthodox" (further 3% were Sephardi, which technically eschews the title "Orthodox").