Palm Springs YTO
Music is separated into "bars" with a set number of beats or pulses.
4/4 tells us there are four pulses per bar and a quarter note represents one full pulse or beat.
The system of music notation is based on mathematical proportions: whole, half, quarter, eighth and sixteenth notes.
These values may divide the musical bar in any combination as long as each beat is represented by a tone or a silence.
Between the harmonic series and using perfect fifths to find new notes, the western scale settles on twelve chromatic steps and seven natural notes between each octave.
These are represented by the twelve total keys (white and black) between the octaves on a piano.
A# is not the same as Bb, but it is close enough that we don't mind using the same pitch for both notes.
On the piano, if I raise the pitch A one half step I play the same key as if I lowered B one half step. So A# and Bb are the same key, but not the same note.
For the voice and string instruments, this is not a problem, but when creating keyboard instrument and limited by 10 human fingers and logistical space, we had to make some choices.
Therefore, in today's system, A# and Bb are regarded as the same note in the majority of performances.
However, when you hear the top orchestras in the world play, you will hear the difference between A# and Bb.
The half step is the smallest musical unit and the whole step the second to smallest.
A whole step is synonymous with "major second" and a half step with "minor second".
Each fret on a guitar is a half step just as every key on a piano (black and white).