Notes & the Keyboard

Every key on a piano sounds a single note - a pitch with a fixed frequency. Press a key below and you'll hear it. Hold several at once to build a chord; the keyboard is fully polyphonic.

Notice the black keys carry two names, like C♯ / D♭. That single key is one pitch, but it can be spelled two ways depending on the musical context - a distinction that matters once we reach scales and key signatures. The white keys each have just one name (C, D, E, …).

Play with mouse, touch (try several fingers at once), or slide across the keys. You can also play with your computer keyboard - the Z row is the lower octave, the Q row the upper, and the ↑/↓ arrows shift octaves. Drag the top edge of the keyboard to resize it. Have a MIDI keyboard? Use Connect MIDI in the bar above the keys.

Octaves and registers

Twelve notes are nowhere near enough to fill everything we can hear, so they repeat. Each repetition is a higher or lower register, and the distance from a note to the next note of the same name is an octave. Physically an octave doubles the frequency: A4 is 440 Hz, A5 is 880 Hz, A3 is 220 Hz. Because the order of notes is identical in every octave, anything you learn in one register you have learned in all of them. A full piano spans about seven octaves, 88 keys from A0 to C8.

Why C, and middle C

The number after a note name, like C4, tells you its register. Each register starts on C, and the C in the middle of the piano, C4, is called middle C. C earns that starring role because it is the only note whose major scale uses nothing but natural notes, the plain white keys, which is also why registers are counted from it.

Twelve notes, fixed in pitch

Those twelve notes divide the octave into twelve equal half-steps, a system called twelve-tone equal temperament. Their pitches are pinned down by a shared standard, with A4 fixed at 440 Hz, so that musicians everywhere tune to the same reference and can play together in tune.