sheet music history
Some history (not essential reading but hopefully informative)
How is it we have a system like this where there are 12 notes per octave and they aren't named A through L? A Byzantine era system with 7 note names has evolved to be what we today know as the do-ra-mi-fa-so-la names (known as solfège). And these names are still used in many parts of the Western world, while in English speaking countries, the A through G naming convention is primarily used.
Around the turn of the 1st millennium, an Italian Benedictine monk created the staff notation that has evolved over the last 1000 years to the sheet music notation we have today. His staff represented 7 notes with alternating lines and spaces as does modern sheet music. In that era, there was little precision in definition of the actual sounds, or tones, of these notes. But it clear that what has evolved over time is a scale with notes not sounding equally spaced. In fact there are some "gaps".
Over time (through the Medieval and Renaissance) the 7 note scale proved to be not enough of a range for musicians and so additional notes were added in between these notes to "fill in the gaps". Eventually, we end up with a 12 note scale wherein the notes sound to the human ear as equally spaced when played sequentially. In science, when things change, so do the methods and terminology. In music, not so much. As a result, there was never a movement to redefine music terminology to convert to a system with 12 note names such as A through L. Instead, clinging to traditional terms, the additional 5 notes of the expanded scale were given names that reflect their relationships to the original 7. For example the "new" note between A and B can be referenced as the one "higher than A" or "lower than B". Thus, the terms sharp and flat respectively came into being. As you will learn, not redefining the terminology leads to a ripple effect for other aspects of music theory.
The scale reflected the
For example, take the term octave described above. The "oct" is from the Latin cardinal number "octo" for 8. But wait, aren't there only 7 notes in the original scale? This is because, like the Sound of Music tune, it starts and ends on the same note. So, the 8 is equal to the 7 notes in the scale plus the first note in the scale again. Thus this name can be a little confusing at the outset. But even more so after the additional 5 notes are added. To reflect this change, it would have been logical to have a new name based on the Latin cardinal number for 13, tredecim. Or more appropriately, based on the cardinal number for 12, duodecim to accurately reflect the number of notes in the scale. But obviously, this term is not going to be redefined and the best we can do is accept the term octave while understanding what it really means.
Around 1700, the first piano was produced by Bartolmeo Christofori with a keyboard that physically reflects the "old" notes, with white keys, and the "new" notes, the black keys. Ignoring history, there's no logical reason to discriminate between the old and new notes because they are equals among a 12 note scale. For practical reasons, however, you would not want to play a keyboard with 88 identical width white keys. So the black and white key layout does make it possible to identify a note by its unique location with respect to the "gaps" in the range of black keys (between B and C and between E and F). In addition, the design of recessed and thinner black keys reduces the overall width of the 12 note scale, and thus the entire keyboard.
Interestingly, there is today an American manufacturer, Dodeka, of a redesigned keyboard which does have all keys of equal length and width. So none of them are recessed and each is narrower than the standard keyboard white key. In order to identify notes on this keyboard, there are color coded keys to match their own redesigned color-coded music notation. This notation displays all 12 notes on the scale so there is a one-to-one mapping from sheet music to keyboard which makes a lot of sense. The downsides sides to this approach are threefold. (1) you'll have to buy their special piano with this keyboard. (2) Because of the 12 note scale there are a lot of lines to read and process and the sheet music requires more space per line. (3) It is so different from traditional notation, that if you ever want to learn it you basically have to relearn all aspects of reading music from scratch. WYSIWYP has less of a deviation from traditional notation (e.g., 7 note scale) and should not be as difficult a transition. And you can play your own piano.