A piyyut or piyut (plural piyyutim or piyutim, Hebrew פּיּוּטִים / פיוטים ,פּיּוּטִ / פיוט; from Greek ποιητής poiétḗs "poet") is a liturgical poem, mostly in Hebrew or Aramaic, usually designated to be sung, chanted, or recited during religious services. The author of a piyyut is known as a paytan or payyetan (plural paytanim). The most follow some poetic scheme, such as an acrostic following the order of the Hebrew alphabet or out the name of the author. The earliest piyyutim were “overwhelmingly [from] [Eretz Israel] or its neighbor Syria, as only there was the Hebrew language sufficiently cultivated that it could be managed with stylistic correctness, and only there could it be made to speak so expressively.”
Many piyyutim are familiar to regular attendees of synagogue services. For example, the best-known piyyut may be Adon Olam ("Master of the World"), whose poetic form consists of a repeated rhythmic pattern of short-long-long-long, and it is so beloved that it is often sung at the conclusion of many synagogue services, after the ritual nightly saying of the Shema, and during the morning ritual of putting on tefillin. Another well-beloved piyyut is Yigdal ("May G-d be Hallowed"), which is based upon the Thirteen Principles of Faith developed by Maimonides.
Hymn added to the older liturgy that developed during the Talmudic era and up to the seventh century. The oldest piyyuṭim are anonymous. They were written during the era of the early Geonim (c. 7th cent.) and are embodied in the prayer-book. They show an attempt at meter, and, as in some late Biblical poetical compositions, the successive lines are often alphabetically arranged. Examples of this kind are found in the Sabbath morning prayer "El Adon, ha-Kol Yoduka," in the penitential prayers "We-Hu Raḥum" for Mondays and Thursdays.
The hymns for holy days and some special Sabbaths are more specifically called "piyyuṭim," or often, wrongly, "yoẓerot." They are divided according to their place in the regular liturgy. Those that are inserted in the evening prayer ("'arbit") are called Ma'arabiyyot; those inserted in the first benediction of the morning prayer are called Yoẓer, from the benediction "Yoẓer Or"; in the second benediction, Ahabah, from the initial word of that benediction; those inserted in the benediction following the Shema'are called Zulat, from the keywords "En Elohim zulateka," or Ge'ullah, from the benediction "Go'el Yisrael."
The days on which piyyuṭim are inserted in the regular liturgy are the holy days (including Purim and the Ninth of Av) and a number of Sabbaths which possess special significance, as the Four Parashiyyot, including the Sabbaths falling between them ("Hafsaḳot"); the Sabbaths on which New Moon falls; Ḥanukkah Sabbath; Sabbath Bereshit, when the first portion of the Torah is read; Sabbaths on which the Scriptural reading his some special significance, as when the sacrifice of Isaac (Wayera), or the Song of Moses (Beshallaḥ), or the Ten Commandments (Yitro), or the law of the Red Heifer(Ḥuḳḳat) is read; and other Sabbaths. The persecutions during the Crusades constitute the theme of the "Zulat". Special events, as a circumcision on the Sabbath or a wedding during the week, are celebrated by appropriate piyyuṭim. On this point the various rites, as the Ashkenazic, the Polish, the Sephardic, the ltalian, those of Carpentras and Oran, Frankfurt-am-Main, Worms, and Prague, and other prominent old communities, differ very greatly, as they differ also with regard to the pieces selected for the holy days. In general, however, every minhag has given preference to the works of local authors.
Opposition to Piyyuṭim
The payyeṭanim, like the troubadours, conceived their poetry as something that possessed no liturgical character in the strict sense of the word. The degree of approval with which these hymns were received, or of personal respect which the author, in many instances a local rabbi, enjoyed, decided for or against the insertion of the piyyuṭim in the Maḥzor of the congregation. Opposition to the inclusion of the piyyuṭ in the regular prayer as an unlawful interruption of divine service is found as early as the eleventh century. Other objections, from the esthetic standpoint, and on account of the obscure and often blasphemous language used, have been presented in a masterly criticism upon Ḳalir's piyyuṭim by Abraham ibn Ezra (commentary on Eccl. v. 1).
The Reform movement resulted in the general disuse of the piyyuṭim even in synagogues in which otherwise the traditional ritual was maintained; but in such synagogues and even in almost all those which use the Reform ritual, some of the most popular piyyuṭim for New-Year and the Day of Atonement have been retained.
Sources: http://www.jewishencyclopedia.com/view.jsp?artid=360&letter=P&search=Anim%20Zemiros
Selection of piyutim: http://www.piyut.org.il/about/english/
