Kitniyot are a category of foods defined by Jewish law and tradition which Ashkenazi Jews (Jews from Eastern Europe, Germany, etc.) refrain from eating during the Biblical festival of Passover.
Kitniyot including maize (North American corn), as well as peas and legumes, which Ashkenazi Jews do not eat during the seven days ofPassover, although Sephardic Jews do.
Jews are prohibited by the Torah (Exodus 13:3) from eating Chametz: Chametz is any food that rises or can be leavened, baked from the grain of wheat, barley, spelt, oats or rye. According to rabbinic law, the only way in which "Kosher le-Pesach" (Passover-approved) food can be made from these foodstuffs is by quickly baking goods made from them at a very high temperature, in order to prevent any rising or nautural leavening.
The reason for the prohibition of kitniyot are complex. In European countries where Ashkenazi Jews lived, it was often too difficult to distinguish between meal ground from chametz and meal ground from kitniyot; further, these food products in the market were stored nearby and sometimes mixed together to a small degree. Jewish law is extraordinarily stringent about the prohibition against even the slightest amount of chametz in the house during Passover, much more so than the regular laws of keeping kosher. Thus a tradition developed to avoid these products altogether, and this eventually developed into what most of the European Jewish community accepted upon themselves as a custom that nearly had the status of a law, a minhag\.
Sephardic and Yemenite Jews generally do not accept the necessity of this minhag, and thus eat kitniyot on Passover. Some Ashkenazi Jews in Israel who have married Sephardic Jews adopt the Sephardic custom; this often occurs with Orthodox rabbinic approval - a noted leniency, since Orthodox rabbi usually hold that one may not reject the minhagim (customs) of one's parents. In light of the gathering of Jews of all ethnic groups back in the land of Israel, Masorti Jews (Israel Conservative Jews) hold that all Jews living in Israel may safely abandon the minhag of refraining from kitniyot.
