This piano keyboard has 12 keys. It has 7 white keys and 5 black keys.

When you play any key on a piano, you hear a musical note sound. In music theory, each note sound (or pitch) has a note name. The same pitch or note can have more than one musical note names.

They are called enharmonic notes. Before we get to them, we need to learn about the middle C note and the musical staff. And after that, the accidentals.
Back to the 12 keys piano keyboard, these 7 white keys and 5 black keys are within one octave. A standard 88 keys piano contains slightly more than 7 octaves.

3 keys in 0 octave and 1 key in 8 octave.

The pitch is higher as you move from left to right on the piano. A note that is higher in pitch has a higher frequency. The frequency of a sound is the measure of how frequently a sound wave travels to your ear per second.
Let’s look at the key frequencies example below. It summarizes the relationship between pitch and frequency in 3th and 4th octave. Any musical note that is an octave higher has twice the frequency. For more information, click on the image.
In next lesson, we will learn the piano note names.