There are many ways to start talking about music, now after some experience of teaching theory I notice that starting here tends to yield the best results. For some time it will seem that my approach is not very useful, but trust me it will click later on!
A Major scale is a type of scale, and a scale is a collection of notes. For now let's not worry about what notes belong to a scale, but let's look instead at the index of notes!
By index I mean the number that represents a note inside a scale. Many scales have 7 notes, some other scales have more than or less than 7 notes and they are commonly referred to as “artificial scales” or “synthetic scale”.
For now we will focus on scales with 7 notes, and to get fancy up in here we will call these type of scales “diatonic scales”.
I like to look at the meaning of new words, to me it's helpful when confronted with weird stuff like diatonic. Diatonic comes from Greek, dia means through or belonging to, and tonos means tone. So Diatonic literally means “that belongs to a tone or a scale”.
|That belongs to a Major scale
||Does not belong to a Major scale
So a non diatonic scale is a scale not alike a major scale:
||Not a Major Scale
||Not 7 notes, can be more or less notes
A Diatonic scale follows certain “rules”, more less it follows a pattern. For now we will not focus on said pattern, instead on the note index. In musical terms, the index is referred to as the scale degree.
Here's the scale degrees of a Major scale:
Looks simple right? Just numbers 1 to 7... Well it's because it is simple! These numbers from 1-7 have multiple meanings and if you understand all of them you will very easily understand melodies, intervals, chords, song progressions, available tensions and much more!
Now, let's think of notes for a second.....
Notes have letter names, they are named after letters from the alphabet. The note names are so intertwined with the diatonic major scale that there are only 7 letter names from the alphabet to represent the 7 notes from a diatonic scale. Sounds confusing? Take a look at this: The note names are A, B, C, D, E, F and G.
7 letters from the alphabet for 7 scale degrees, 7 notes to fill a 7 note scale.
But if you look at an instrument you'll notice there are many more notes than just 7. A full sized grand piano has 88 keys! Well, turns out that the note names repeat, You have the notes A though G and then back to A, and so on.
On a piano, the notes A through G are represented by the white keys. And there are some black notes in between some white keys. Those black notes don't have names for themselves. They are called in reference to the notes around them.
For example the note C sharp is the note just above the note C. And the note A flat is the note just below A.
“Sharp-ed” notes are referred to with the simbol “♯”, and “flat-ed” notes are referred to with the symbol “♭”. Now on the internet it's easier to type # and b for sharps and flats.
In addition to sharps and flats we also have “naturals”, meaning a note without any modifications. B natural is the same note as B with no sharps and flats. The natural symbol is “♮” and due to its function it is often written out in English (for example “play an F natural instead of an F#”).
Notes that don't claim to be flat or sharp are natural by default. So C is the same as C natural.
|To raise a note in pitch by 1 note
||To lower a note in pitch by 1 note
||nor # or b
|♯, or #
||♭, or b (in lowercase)
Why am I going on and on about sharps and flats?
Because we use them for tell apart a Major scale from other scales!
For example, this is a Major scale:
while this is not a major scale:
This is some other scale, but because the 7th degree is flattened it's some other scale. If the 7th were a natural it would be a Major scale!
This is a long way to say that a Major scale is 1-7 and nothing else!
A Diatonic scale is a scale related to the Major scale, all diatonic scales share many characteristics, one of them is that they have 7 notes. So the scale above (with the flattened 7th) is not a Major scale, but it's still a Diatonic scale. Because it's related to the Major scale, because it also has 7 notes. There are other characteristics that play in here but we will go over them later.
So that's it! The Major scale is 1 2 3 4 5 6 7! Later we will look at the names of the notes rather than the numbers, but for now that's it! What about 1 2 b3 4 5 6 b7? That aint Major, it has flats... and what about 1 2 3 #4 5 6 7? Nope, sharped 4, not Major!