Heb. Siddur (‘Arrangement’), a book containing the daily and Sabbath prayers. The book containing prayers for the festivals is known as a Mahzor (from a root meaning ‘to come round’, i.e. for use when the festivals arrive). All prayer books have the same basic features (see LITURGY) but each rite has its own additions and version, for example, the Ashkenazi Siddur, the Sephardi Siddur, the Italian Siddur, in modern times the Reform and Conservative Siddurim (plural of Siddur), and others, each in conformity with the ideological stance of the compilers and users.
In Talmudic times the prayers were recited by heart and there were no written orders of service at all. The first Prayer Book was compiled in the ninth century by Amram Gaon (see GEONIM), and is known as the Seder Rav Amram Gaon. This was followed in the tenth century by the Siddur of Saadiah Gaon. Since then, especially after the invention of printing, numerous prayer books have been published. The Kabbalists have their own Prayer Book, of which there are a number of different versions. In these the special ‘intentions’, kavvanot (see KAVVANAH), of the Kabbalah are given to allow the worshipper to concentrate on them in his prayers. There are also a number of Hasidic prayer books, usually with comments offering guidance to the particular branch of Hasidism for which they are intended. Material was added to the Prayer Book from time to time, often at the mere whim of the printers.