What is the purpose of a cigar punch?

Hand-rolled cigars have a cap--it's a little piece of tobacco stuck to the head, and it's there to keep the cigar from unraveling. You can't smoke the cigar with it intact, so you need to remove some. A cigar punch puts a hole in the cap. Cigar cutters and cigar scissors do the same thing, so which one you get is a matter of personal preference.