I can be 0-10, and even to 18.5, I may also come in half a size. New or old, narrow or wide, just take your pick, but make sure you know how to use a measuring stick. I can be muddy, smelly, expensive, colorful, plain or nice.You can also tie me, untie me, or leave me by the door, but I know your feet will thank me once you’ll wear me more. What am I?