In talmudic law (Pes. 35a), the term hamets applies to any of the following species of grain and their derivatives which, through contact with water, have been subjected to a leavening process: wheat, barley, spelt, rye and oats. Sephardim permit rice and legumes, while Ashkenazim add these to the prohibited list.   

The strict rabbinic laws on hamets exclude the use of all domestic utensils, crockery and cutlery used in the preparation of such food during the year. For the most part, crockery used during the year may not be utilized on Passover on the assumption that earthenware absorbs an element of the hamets for which it was used. Separate dishes are therefore kept especially for Passover. Metalware, e.g., knives and forks formed of one metal piece, may be "kashered" (rendered fit) for Passover use and so may metal pots which have been used for boiling food. The general method for kashering these items is by dipping them in boiling water after they have been thoroughly and meticulously cleaned. Glassware is non-porous and may be kashered by immersion in water for three days -- changing the water each day -- followed by a thorough cleaning. The approach of Conservative Judaism is to dispense with the soaking of glassware based on the assumption that a cleaning with modern detergents is equally effective. Metal utensils that have been used for frying, e.g., frying pans, can only be kashered by holding them over fire to burn off every particle of hamets. However, despite the permissibility of kashering non- porous food utensils, the common observant Jewish household finds it preferable to keep a separate set of such objects especially for the Passover festival.   

Today, the composition of some modern materials is so complex that it is hard to determine its porosity or non- porosity. For this reason, certain items of "Corningware" and hard plastic are subject to different opinions by rabbinic authorities. The Orthodox rabbi is usually less willing than the Conservative rabbi to consider these materials "kasherable." In cases of doubt the layman is advised to seek the guidance of his rabbi. Reform Jews do not change their utensils. Other preparations include (1) The search for leavened food (Bedikat Hamets): on the eve of 14 Nisan a formal search is made for any leaven which is still in the house. This is then put aside and burned on the following morning; (2) The sale of the unleavened food (Mekhirat Hamets): any leavened food, drink, or other commodities which cannot be removed before Passover and which are intended for use after the festival are sold to a non-Jew for the duration of the festival. This done, any leaven in the house of the Jew, strictly speaking, does not belong to him. In this way he avoids transgressing the biblical law against the possession of leaven or its retention in his house during Passover. Because of the legal technicalities in this kind of sale, it is usual for the rabbi to carry out these arrangements on behalf of the community. Leavened food or drink which remains on the premises of a Jew and which has not been disposed of by such a sale is forbidden for use even after the festival.   

The Seder is the order of the home ritual observed on the first two nights of Passover (in Israel and among Reform Jews, on the first night). This is the most important observance of the festival as well as one of the most widespread among the Jewish people. Its purpose is to dramatically commemorate the slavery and the Exodus. This is done through symbol, ceremony, special readings, and hymns.

Liturgy. The liturgy for Passover contains the statutory festival additions of HALLEL and the ADDITIONAL SERVICE. The readings from the Pentateuch are Exodus 12 (the story of the Exodus from Egypt) on the first day and on the seventh day, Exodus 13-15, which contains the account of the crossing of the Red Sea on the seventh day after the Exodus. A liturgical feature unique to Passover is the prayer for DEW recited before the Additional Service on the first day. The Yizkor or Memorial Service is read in Ashkenazi synagogues on the last day.