Hi,
Chametz is one, if not the main, properties of Passover. Well better say the absence of it. It is basically anything made of wheat (or other 4 species of grain) with added water and left to stand more than 18 minutes. After 18 minutes, agents raising start to work, and the dough starts to rise.
The idea behind it is, is that the Israelites had no time to let the dough rise and bake it as is, when they finally were allowed to let free out of Egypt in the Bible stories. So they did not ate any Chametz, but only Matzah. So in memory of it, the Judisam allows Jewish eating only Matzah for the 8 days of Passover.
So we are not allowed to eat Chametz in Passover. As you still have some of it before Passover, you can “sell” it before Passover and “buy” it back after it (especially companies that use it all year around like graineries). Supermarkets are not allowed to sell of it from that point on, and they cover the shelves with it during the holiday.
But not only Chametz is not allowed, but anything that might contain a bit of it. Or, in other words, anything that was not made especially for Passover and was kept clean from it during the manufacturing process is not allowed during Passover.
So you find yourself buy things that, in my opinion, are absurd – food for dogs and cats, tea bags, cleajing materials etc.
Chametz even caused the Israeli government to fall. The Chametz law prevented visitors in the hospitals from bringing in Chametz in Passover. The law asked the gaurds in the hospitals in Israel to check the visitors’ bags for Chametz and confiscate it.
Take Care
Gad
Covered shelves in the supermarket’ aisles near our house so to prevent you from buying it