Half Steps and Whole Steps

Before we begin talking about accidentals, we will need to establish some terminology.  The distance between two consecutive notes on the piano keyboard is called a half step; two half steps make up a whole step.

Looking at the above illustration, the distance between B and C is one half step.  The distance between A and B is one whole step (there's a black note in-between).  The distance between F and the black note immediately above it (to the right) is one half step.

That said, in order to reference the black notes, we will use two symbols:  sharps and flats .