Intervals are the ‘spaces’ or ‘differences’ between the pitches of two notes. In Western musical theory, intervals make it possible to analytically construct scales, chords, and progressions, making it much easier than memorizing the different notes of each individual scale.
For simplicity, the C will be the root note of all examples. The following is a chart of all the intervals on the guitar with respect to the root note C as well as their corresponding symbol.
C#-Minor second -m2
D-Major second -M2
Eb-Minor third -m3
E-major third -M3
F-Perfect fourth -P4
G-Perfect fifth -P5
G#-Minor sixth- m6
A-Major sixth -M6
Bb- Minor seventh- m7
B- Major seventh- M7
This repeats itself with the ‘eighth’ interval being the root and all other notes following it have the same relationship as above. It would be helpful to learn and memorize these relationships as they will pay off exponentially in terms of musical application. (For this example, augmented and diminished intervals were skipped).
Scales are simply different intervals with respect to the root note that define that specific scales sound. When dealing with intervals, certain ‘equations’ can be used and manipulated to create and rearrange differing scales. Major scale formula- 1 2 3 4 5 6 7.The numbers correspond to the intervals of the scale, so 2 is actually the major second(where minor second would be b2, or flat second). What this means is that intervals used in the major scale have this relationship with the other notes with the original root note. The root note can change, causing the notes of the scale to change but not the actual scale formula(difference between the notes). The minor scale is similar to the major scale but the interval formula has some minor changes, specifically the 3rd, 6th, and 7th intervals are all flatted(moved one step down).
There are multiple ways of looking at chords but one of the most useful is to look at them as parts of the scale, with the original interval formula of the scale remaining the same, played together to form one sound or piece of the scale. For instance, a major triad(three specific intervals in the scale) is created by taking the root, major 3rd, and perfect 5th intervals(1 3 5). If you know the notes of the scale your trying to construct chords from, then its as easy as playing those separate parts of the scale. Minor triads can be formed by looking at the minor scale and taking the root, minor 3rd, and perfect 5th intervals(1 b3 5), or if you know the major scale of that same root then you can just flatten, or go one step down.
Learning and memorizing these simple definitions of intervals and their relationship to chords and scales will undoubtedly improve ones own understanding of music and thereby improve their overall musical ability, not only allowing greater creativity but also a way to communicate and express your music to fellow musicians and vice-versa.