For those that have a serger or overlock machine, it can be a pain to change the thread. I'd always just use white on whatever I was making, just to avoid having to re-thread the thing.
But my little sister, Lynette taught me a trick a while ago that makes it so easy to switch your thread to a new color so it can match whatever you're sewing. Especially since I'm not a perfect sewer, I don't want to draw extra attention to my seam allowances.
Hope this helps and excuse the fact for some reason I couldn't remember the name for the hand wheel...you get the point though.