A piping bag, also known as a pastry bag, is a cone-shaped bag that you fill with icing, frosting, or sauce. You apply pressure to the bag to dispense frosting, icing, or sauce in a specific pattern to make your dish beautiful and tasty. You can make a piping bag by filling a resealable plastic bag and cutting the corner off. If you don’t have a plastic bag, you can cut a triangle out of parchment paper and fold it into a cone. If you want to store any left-overs, use a plastic bag since it can easily be packed away. If you have a lot of different icings that you need to use, opt for parchment paper since it’s cheap and disposable.