Q. What are kitniyot?
A. Ashkenazim customarily do not eat peas, beans, corn or rice (kitniyot) on Pesach, not that these are chametz according to the strict definition but because they resemble grains such as wheat and barley and can be ground into a type of flour that can be used for baking.
The Sephardim do not follow this practice and indeed rice was often a staple on Pesach for them.
Even though peanuts are not grown in the fields like or with grains, and are nuts rather than legumes, some communities have the custom of refraining from using peanuts and peanut oil on Pesach.