Approximately 5 million of the world's 13 million Jews live in the United States. There are basically three major movements in the U.S. today: Reform, Conservative and Orthodox. Orthodox and sometimes Conservative are described as "traditional" movements. Reform, and sometimes Conservative are described as "liberal" or "modern" movements.

Orthodoxy is actually made up of several different groups. It includes the modern Orthodox, who have largely integrated into modern society while maintaining observance of Jewish Law (halakhah) , the Hasidim, who live separately and dress distinctively , and the Yeshivish Orthodox, who are neither Hasidic nor modern. The Orthodox movements are all very similar in belief, and the differences are difficult for anyone who is not Orthodox to understand. They all believe that God gave Moses the whole Torah at Mount Sinai. The "whole Torah" includes both the Written Torah (the first five books of the Bible) and the Oral Torah, an oral tradition interpreting and explaining the Written Torah. They believe that the Torah is true, that it has come down to us intact and unchanged.

Reform Judaism does not believe that the Torah was written by God. The movement accepts the critical theory of Biblical authorship: that the Bible was written by separate sources and redacted together. Reform Jews do not believe in observance of commandments as such, but they retain much of the values and ethics of Judaism, along with some of the practices and the culture.

Conservative Judaism grew out of the tension between Orthodoxy and Reform. Conservative Judaism maintains that the truths found in Jewish scriptures and other Jewish writings come from God, but were transmitted by humans and contain a human compontent. Conservative Judaism generally accepts the binding nature of Jewish Law, but believes that the Law should change and adapt, absorbing aspects of the predominant culture while remaining true to Judaism's values.