By the early Middle Ages, various forms of ritual had developed from the ancient Babylonian and Palestinian (Erets Israel) traditions. Essentially, the differences involved those types of liturgical poetry---Kinot, Piyyut, and Sḥot--- which certain communities had adopted. In the course of time each ritual underwent changes and "cross-fertilization" between certain groups occurred.
The Babylonian tradition gave rise to a number of separate rituals in Spain, Portugal, and southern France, parts of North Africa, and the Near East. Its most important offshoot was nusaḥ Sefarad, the Spanish rite now preserved by Sephardim in Israel, Britain, Holland, the the United States, and other lands. Some characteristics of this prayer rite are the arrangement of the Morning Service, the wording of Kaddish and Kedushah, the formulation of the Grace After Meals, and procedures for the Reading of the Law. Closely related to the Sephardi rite is nusaḥ edot ha-Mizraḥ, the "Oriental" communities' form of worship, which is indigenous to North Africa, Syria, Turkey, and Iraq, and which now largely survives in Israel. This is true also of minhag Téman, the Yemenite ritual based on the prayer books of Saadiah Gaon and Maimonides, which the Sephardi tradition clearly influenced. Among other rites that have disappeared was that of Provence, an unusual mixture of traditions that survived until the 19th century.
The Palestinian group had fewer representatives. One, the Romaniot or Byzantine rite (nusaḥ Romania), held its own from Turkey to Greece and Sicily until the 16th century, when Sephardi refugees imposed their own form of worship on the indigenous Jewish communities. More tenacious, despite foreign influences, was the Italian or Roman rite (minhag Italyani), possibly the oldest in Europe, which is still practiced by Italian Jews (including those who have settled in Jerusalem). Some of its characteristics are shared by the Ashkenazi rite, others are found nowhere else. The Italian prayer book was the first of its kind to be printed (1485-86). Two other prayer rites developed in the Carolingian Empire. Of these, the North French rite survived the Middle Ages only in three small Italian communities. The other, nusaḥ Ashkenaz, spread with recurrent expulsions of the Ashkenazim from the Rhineland and Central Europe to Poland, Lithuania, and Russia; to the west and south of the Elbe; it underwent little change, but to the east it acquired some distinctive features and became known as minhag Polin. It is this "Polish rite," styled minhag ha-Gera (because of its association with Elijah the Gaon of Vilna)) in Israel, which now has the largest following throughout the Jewish world.
Those Ashkenazi Jews who embraced ḥasidism adopted a modified version of the Sephardi rite based on that of Isaac Luria (Ari) and therefore known as nusaḥ ha-Ari. It incorporates various Sephardi liturgical elements (in the Kaddish, Kedushah, etc.), but is still Ashkenazi for the most part. Since 1948, attempts have been made in Israel to evolve a "unified rite" (nusaḥ aḥid) suitable for Jews of different origins, both a prayer book and a Passover Haggadah (issued by the Chief Rabbinate of the Israel Defense Forces) having that aim in view. Apart from minor changes (e.g., rewording prayers related to the Temple sacrifices), Conservative Judaism has retained the traditional Ashkenazi rite. In line with its own theological views, however, Reform Judaism has made sweeping changes and substitutions over the years, although some omissions have been restored.
The term nusaḥ also has the connotation of a musical style employed in the liturgical rendering of prayers. All existing rites have preserved such melodic traditions, and anyone capable of interpreting them with accuracy and tunefulness is said to "know" or "possess" a good nusaḥ. There are standard modes for daily and weekly prayers, special modes for reading the Pentateuch and the Five Scrolls, as well as solemn motifs for portions of the service on Festivals and on the High Holidays. See also Cantor and Cantorial Music; Cantillation; Liturgy; Maḥzor; Music and Song; Prayer; and Prayer Book.