think of this: what if you need to find your car keys in a box filled with lots of kids toys, socks and all kinds of useless things you have at home? that's how it looks like when you have many vars in one place (e.g. global scope). now, if the only things in that box are car keys, one toy car and one sock, finding keys in there is no-brainer - similarly, having all your vars global is not a problem if you only have so much of them.