Piano eTutor: Learning piano serves only one purpose: teaching piano. But it makes users feel the convenience it can bring. Because this application takes full advantage of the convenience of modern mobile devices. What makes users see most clearly is that it uses real interactions. They will understand the lesson immediately. It is like you are actually hiring a piano tutor. Moreover, advanced lessons are also provided in this application. With just one application, users can quickly learn how to play the piano. and if the practice time is long enough, they can even play this musical instrument proficiently.