What is a Touring Plan?

Generally when I go to the parks I don't have much of a plan. I was checking out information about Magic Kingdom Touring Plans and it got me wondering if I was missing something. If you don't know what a touring plan is, it's simply a pre-determined approach to maximizing the amount of attractions you see while you're in a park. I'm pretty experienced so I don't need them as much, but for neophytes it can definitely help to have a plan before you go. Even a "pro" like me can still make mistakes in the heat of battle.