The term "denatured" is typically used when one talks about ethanol (drinking alcohol). Denaturing means that something unfit for human consumption (gasoline, methanol (wood alcohol), etc.) is added to the ethanol so people can't drink it (and so the government doesn't lose out of collecting taxes). This is the case with gasoline grade ethanol. Typically it is 97% ethanol and 3% methanol or gasoline.
Isopropanol is a different type of alcohol, and is completely unfit for drinking. When the bottle says 90% rubbing alcohol, typically the other 10% is water. It is possible for a small quantity of the other alcohols and possibly acetone to be present, but they are not intentionally added. Like the other alcohols (methanol and ethanol), isopropanol is very volatile (evaporates easily). It is a popular component in cleaners because it is cheap and it helps the cleaner dry relatively quickly.
Scott
*edited spellings*
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Edited by Strapper_Squared on 3/22/2012 at 8:25 PM