a straw man is telling person A that argument B is wrong, therefore person A is wrong, when in fact person A was making argument C.

it is a trick to confuse your opponent and any spectators. it is most often employed by people too stupid to discern between argument B and argument C in the first place, which is to say it is most often employed inadvertently.

amusingly, most times when people accuse someone else of making a straw man argument, they then proceed to immediately make a straw man argument themselves in explaining the claim.

edit: mistyped.