Tin foil Tin foil Tin foil, also spelled tinfoil, is a thin foil made of tin. Actual tin foil was superseded after World War II by cheaper and more durable aluminium foil, which is still referred to as "tinfoil" in many regions. Foil made from a thin leaf of tin was commercially available before its aluminium counterpart. In the late 19th century and early 20th century, tin foil was in common use, and some people continue to refer to the new product by the name of the old one. Tin foil is stiffer than aluminium foil. It tends to give a slight
FOIL method FOIL method In elementary algebra, FOIL is a mnemonic for the standard method of multiplying two binomials—hence the method may be referred to as the FOIL method. The word "FOIL" is an acronym for the four terms of the product: The general form is: Note that is both a "first" term and an "outer" term; is both a "last" and "inner" term, and so forth. The order of the four terms in the sum is not important, and need not match the order of the letters in the word FOIL. The FOIL method is a special case of a more