Musicians typically choose to tune their instruments to the frequency A440, meaning that the A note above middle C resonates at 440 hertz. However, some artists choose to tune their instruments to alternate frequencies.
The Alternate Tuning Piano allows you to play piano, using your computer's mouse or keyboard, in any of the available frequencies.
Keys on the piano can be played using the labeled letters and symbols on your keyboard.
A440 is the most common frequency that instruments are tuned to.
It's likely that every song that you can name is tuned to A440.