Matzo, matza or matzah is an unleavened flatbread that is part of Jewish cuisine and is a predominate part of hte Passover festival.
Containing egg and sometimes juice, egg matzah is commonly considered a variation that cannot be used as a acceptable bread during Seder. Acceptable matzah must only contain flour and water.
The matzah may only be made from one of the five species of grain that can become chametz (leavened). These grains are wheat, rye, barley, spelt and oats.