Hopefully by now you have got a good idea of what scales are. However, they are much more than just an interesting ways of putting notes into an order: scales form the basis of all music. The character of a scale can be used to mould the features of a piece of music; hence, a tune in a minor scale will be sad or melancholic, while a tune in a major scale is likely to be upbeat or bouncy.
At this point, you are probably wondering what I mean when I say “in a minor scale”? Basically, it means that the tune in question is written and played using only (or mainly) the notes present in a particular minor scale. So if I were to say that a tune is “in A minor”, it means that it only consists of the notes in the minor scale of A (and maybe a few different ones here and there for musical colour), i.e. A, B, C, D, E, F, G. The scale is like the musical alphabet of a tune; because the scale is like the foundation of a tune, it is the main source of character and style for the music.
Amongst all this talk about scales, you may have noticed that the notes in the A minor scale are the same as the notes in the C major scale. The question that immediately springs to mind is: “How can two tunes, that are made up of the same notes, sound different?” The answer to this is all down to chords.
Chords usually form the background harmony of tunes: in piano-playing, chords (and their derivatives) are usually played with the left hand, and the melody is usually played with the right hand. The result is that the melody is blended in with the chords that correspond to the scale of the key in which the tune is written. As such, a tune written in C major will usually include a chord constructed of notes taken from the C major scale, and this will emphasize the character of the tune. The simplest C major chord is C, E, and G all played at the same time. If you were to play this chord on a keyboard, you would see that it is typical of the major scale, i.e. it sounds “happy” or “agreeable”. With chords like this being played, along with the melody, a tune will easily sound upbeat and is unlikely to accidently sound like a tune written in A minor.
This is all general detail, but it must be understood that scales and chords are ribs and spine of any music. They are so important in harmonica playing that they form the basis of where the individual notes are physically positioned on a harmonica.