Origami is the traditional Japanese art of paper folding. Starting in the 17th century AD at the latest, origami has since then evolved into a modern art form. Most models are created by folding a single sheet of paper into a finished sculpture, yet some use many sheets of paper or a type of origami called 3D origami. Models range from very simple and easy to complicated and intricate. One of the best known origami models is the crane.