Chametz means “leavening agents.” Any food or drink which contains wheat, barley, rye, oats, spelt, or any other forms of leaving agents cannot be eaten on Passover.
Some examples of Chametz are:
The searching for Chametz ritual is done the night before Passover begins. Each corner, room, and even your car should be checked for Chametz. Furniture and couch cushions should also be included in the cleaning.
Another tradition many Jews will do is change over their entire kitchen to Kosher for Passover. This means taking all the dishware, silverware, glasses, and all cookware out of the kitchen and replacing it with a set which is only used during Passover time. Instead of changing everything over, some Jews will just use paper and plastic dishware and silverware when eating.
The entire kitchen needs to be Kosher for Pesach. After cleaning everything out, lining the counters, counter tops, and tables with a paper liner is also a common practice.
Any food brought into the home after the cleaning and changing over should only be food which is Kosher for Passover. There are a few websites which make this shopping easier. http://www.ok.org gives a list of products which are considered ok to eat during the 10 days of the Passover celebration.