Q. What is Chametz and what does it have to with Passover?
A. Chametz is "leaven" — any food that's made of grain and water that have been allowed to ferment and "rise." Bread, cereal, cake, cookies, pizza, pasta, and beer are blatant examples of Chametz; but any food that contains grain or grain derivatives can be, and often is, Chametz. On Passover, we only eat Matzah, which is baked in less than 18 minutes not allowing for it to ferment and rise.
Not only do we eat Matzah on Passover, we are also commanded not to eat Chametz for the eight days of Passover. We therefore should check any food we buy for Passover to ensure that it is certified as Kosher for Passover. Chametz is the antithesis of Matzah, which we eat on Passover to recall the haste in which we left Egypt, and the humble faith by which we merited redemption. The flip-side of eating Matzah is getting rid of Chametz — and the egotism and spiritual coarseness it represents.
In addition to not eating Chametz on Passover, the Torah commands us not to own Chametz on Passover. Therefore before the holiday begins we should clean our house to ensure that there is no Chametz to be found. On the eve before Passover (Sunday evening April 17) we search our house to ensure that there is no Chametz. The next morning (Monday morning April 19) we burn any leftover Chametz or any Chametz that we found during our search the night before.
What if you do not want to throw out or burn all of your Chametz (such as liquors). Since the commandment to rid one's domain of Chametz is binding only on a Jew, you can sell your Chametz to a non-Jew, and then buy it back from him after Passover. To do that put all the Chametz that you’ll be selling in a room or cupboard and seal it. Then give the Rabbi power-of attorney to sell your Chametz for you. (The Rabbi will ensure that the sale is legal in Jewish Law and Secular Law). It is important to realize that the sale is not symbolic, but a 100% legally binding transaction.