A curtain tie-back is like a fancy band or a rope that you use to hold your curtains open, so that you can let the sunshine and air coming in from outside. It comes in different materials, such as cloth or metal, and it is usually attached to the wall or window frame. When you want to let your curtains stay open, you wrap the tie-back around them and fasten it in place. That way, your curtains won't cover up the window and you can still see what's happening outside.