The practice of wearing costumes on Halloween came around with the folk history of what Halloween is. It was said that it was the only day that the spirits could walk with the living. The wearing of the costumes was to confuse the spirits into thinking that you too where one of them and they would leave you alone.
Actually, it's the only day of the year that we get to be what we fear, envy and/or respect..."I know, a strange combination. But who's perfect?"--"Oh, by the way...Does anyone really like candy corn?"
The reason we wear costumes on Halloween is because in the 1600's, people would dress up to ward off evil spirits and demons. Now, we do this out of fun and people give us a treat as thanks for warding off the demons. YEAH BOY!!!!!!!!!!!!