On the night before Erev Pesah one is required to perform Bedikat Hames a thorough search of his home for Hames.
The widespread custom is to have somebody disperse pieces of Hames around the home prior to the Bedika; this custom is recorded already in the Kolbo (Halachic work by Rav Aharon of Lunel, 1280-1330). There is a common misconception that this practice serves to guarantee that the head of the household will discover some Hames during the search, since otherwise the Beracha he recited before the Bedika would constitute a Beracha Le'vatala (Beracha recited in vain). As the Bet Yosef notes, however, this is incorrect. The obligation of Bedikat Hames requires searching the home for Hames and eliminating whatever Hames is found; regardless of whether or not one actually discovers Hames, he fulfills the Misva by conducting a thorough search. Hence, the Beracha is perfectly valid even if one's search does not produce any Hames, and there is therefore no need to distribute pieces of Hames before the search in order to ensure the Beracha's validity. Nevertheless, this is the widespread custom and it should be followed. The Arizal (Rabbi Yishak Luria, 1534-1572) maintained that one should distribute specifically ten pieces of Hames.
The Mishna Berura (commentary by Rabbi Yisrael Meir Kagan, 1839-1933) writes that the Hames distributed before the Bedika should be of the hard type, such that it does not leave any crumbs. The objective of the Bedika is to ensure the elimination of the Hames, and this objective is undermined if one leaves Hames crumbs around the house. Moreover, after the wife exerted great efforts to clean the house for Pesah, she might understandably feel distraught upon seeing Hames crumbs in many areas in the house. If for no other reason than Shalom Bayit (domestic harmony), then, it is proper to use hard, solid Hames that does not leave crumbs. Furthermore, the pieces left out for the search should be small less than a Ke'zayit, so that in the event that one does not find a piece, he will not transgress the prohibition of possessing Hames. They should also be wrapped in small bags to ensure that no crumbs are left in the home.
The first Mishna in Masehet Pesahim requires that the search be conducted "Le'or Ha'ner" by candlelight. Hacham Ovadia Yosef writes that nowadays, when our homes are flammable, one may use a flashlight in lieu of a candle. Some Rabbis advise searching for a few moments with a candle as the Mishna requires, and then switching over to a flashlight. It should be noted that the lights in the home need not be turned off for the Bedika. To the contrary, as Hacham Ovadia writes, when one searches for something he wants as much light as possible, so it is preferable to leave the lights on during the search. The flashlight or candle is used for dark areas such as underneath or behind furniture, where the normal illumination is not sufficient.
The Ben Ish Hai (Rabbi Yosef Haim of Baghdad, 1833-1909) writes that while searching for Hames one should carry with him a bowl with salt. Salt, which is long-lasting and used as a preservative, symbolizes stability and endurance, and also has the capacity to ward off harmful spirits and the like.
It must be emphasized that Bedikat Hames is not a five-minute ritual that entails simply searching for the ten pieces of Hames that had been placed around the home. Halacha requires conducting a thorough search in all places where one reasonably suspects that Hames might be present. This includes clothe closets, pockets and the basement, not to mention the kitchen. One must also search the porch, the yard and one's automobiles. In homes with young children, the search must be especially thorough, as children often disperse food indiscriminately around the house. Of course, it is not necessary to search the area where one stores the Hames that he sells for Pesah.
If a person did not find one of the ten pieces of Hames that had been distributed around the house before the search, he is not required to persist until he finds it. As mentioned, the pieces used for this purpose should be less than a Ke'zayit, so one does not violate the prohibition of Hames if some pieces are not discovered, and they are covered by the "Bittul" the renunciation of Hames that one declares after the search.
After the search, the Hames is stored in a safe place in preparation for the burning the following day. One then recites the "Kol Hamira" text three times, renouncing his ownership over Hames in his property of which he is unaware. One does not renounce ownership over the Hames that he plans to burn the following day.
