Similarity measure

A similarity measure is a way of judging how much alike two things are. Think of it like a game of "spot the difference": when you're looking at two pictures, you can look for all the things that are different, and then judge how similar they are based on how many things are the same. In similarity measure, you're doing the same thing, but with numbers. You look at two sets of numbers and then calculate how similar they are to each other. The higher the number, the more similar the two things are.