Matzah balls (yiddish: קניידלעך kneydlekh pl., singular קניידל kneydl; with numerous other transliterations) or matzo balls are ashkenazi jewish soup dumplings made from a mixture of matzah meal, beaten eggs, water, and a fat, such as oil, margarine, or chicken fat. matzah balls are traditionally served in chicken soup and are a staple food on the jewish holiday of passover, though they are not eaten during passover by those who observe a prohibition on soaking matzah products. the texture of matzah balls may be light or dense, depending on the recipe. matzah balls made from some recipes float in soup; others sink.

Source: Wikipedia