Tarps are about the most versatile product in your outdoor arsenal. You can use them to cover gear in your truck, protect the bottom of your tent from rocks and moisture, lay out a picnic, or keep your campfire out of the rain. You can get them simple and cheap, or you can buy specialized versions that pack easily and set up quickly. Which kind you pick depends on how you plan to use it most. Here are three things to think about before purchasing yours.