Suggestions for the next chord in your progression are based on a machine learning algorithm trained on over 10,000 songs. You can use your phone's microphone to recognize the chord that you are playing, and new suggestions will appear. As you build your progression you can change tempo, instrument, and the number of repeats. You can hear any chord and see its diagram on guitar or piano. When you are all done, you can share a progression or save it for later.