Nusach refers to any number of styles of sung or chanted prayers within Judaism. In a nusach service, liturgical prayer texts are set to music that varies depending on the season of the year and the type of service. These styles historically have varied along geographical and theological lines, although the basis of the prayer service is fairly consistent.
The word nusach literally means "text," as a reference to the standardized, liturgical prayers that are set to music in a Jewish service. Usually the text is taken from the Torah, the first five books in the Hebrew scriptures. The text is always sung in the original Hebrew language of the Torah. The most important of these is known as the Shema, which means "hear," after its first word, and translates: "Hear, O Israel, the Lord thy God is one God."
Often, at least some of the text of the nusach does not vary throughout the year. The cantor, or singer, however, changes the tune according to the mood of the occasion. For instance, a darker melody will be used on a day of mourning or fasting rather than on the day of a feast. Within a given nusach tradition, there are standardized tunes to be used for particular times of day, seasons or holidays.
The practice of nusach developed gradually over thousands of years. After the destruction of the temple in Jerusalem in 70 AD, the Jewish people scattered throughout Europe. Eventually, a geographic divide of Judaism developed between the Ashkenazic branch in Eastern Europe and the Shephardic branch in Western Europe. The nusach of each of these two groups evolved separately, resulting in variations in the tune and style of the worship, although much of the essential content of the two branches remained the same.
In the 18th century, the Chassidic movement of Judaism arose in Eastern Europe, which lead many Ashkenazic Jews to revert to the Shephardic style of worship. The founder of the Chassidic movement, Rabbi Israel ben Eliezer, felt that the Sephardic prayer best reflected the mystical aspects of Jewish faith. The Chassidic Jews did not completely adopt the Sephardic nusach, however. Rather than leading to a unification of styles, this movement introduced even greater variation in Jewish worship that continued for several centuries. With the development of mass communications, including the Internet, the various styles have begun once more to influence and meld into one another.