In the past, going to a piano teacher was the most popular way to learn how to play the piano. You could get one-to-one teaching and have the opportunity to learn as much as the teacher knew. If you didn't have private lessons, you could still learn the piano, but you would have to teach yourself. This was easy for some, but very difficult for most. However, with technology developing today, there is at last another way that you can take piano lessons. You can take an online course. An online course is much cheaper than a private lesson. _ . You can take a whole online course in piano for just a fraction  of the money that you would spend on weeks of private lessons. Also, private lessons are usually only one hour per week. So you would have to wait for your next lesson to continue your learning. However, online piano courses are quite different. With an online piano course, you can work at your own pace. You can also take as many lessons per week as you want, or go back and listen to your last lesson if you have forgotten anything. Most adults who want to learn how to play the piano enjoy being able to go back and listen to the lessons again. Of course if you need someone to sit beside you and offer you immediate feedback  as you are playing, you might not get that from an online piano course. However, the lessons online can be viewed  at any time, or as often as you'd like, which means that you can get your own type of feedback from an online piano course. This passage mainly tells us   _  .
the disadvantages of the traditional ways of learning to play the piano the differences between traditional piano courses and online courses why people prefer online piano courses to traditional piano courses the advantages of learning to play the piano through an online course