Yoyos

I have always thought yoyos were a stange toy. First of all, I don't have any idea how the yoyo manages to snape back up, once you let it down its string. Whenever I play with a yoyo, it just falls to the ground, hanging by the end of its string. I think that yoyos can be used to perform amazing tricks, but I found it challenging trying to put my finger in the loop to hold the string. In my mind, I always picture a yoyo in the color yellow. Why yellow? It's so random, why can't I picture yoyos in other colors? My brother loves yoyos, but they irritate me.