I was taking a break today and it occurred to me how I might better explain this concept. Last time I didn't do so well but I think it's worth trying again because, really, how this works is good to know.
For example, on a map the shortest route could look like it's climbing a mountain when really going around it might be shorter and faster, and easier.
You can find more info on this here.
I expect a few of you are laughing away right now (at least I hope so).