People Counter

数人，或算什么，甚至是负的东西

This can be used for doing math, like adding or subtracting one from a number. If you wanted you could count birds that you see, or even keep track of your DogSpotting points, but you'd have to add each of them one by one and won't be able to know why you have them. You could count your steps like all those other fancy step counters but this one doesn't invade your privacy. If you want to take steps without counting them, feel free to step away without counting them. How many step counters do that?