Let's start at the beginning. The very nature of what sound is. If you were to take a piece of sound and put it on a microscope slide, to look at under your microscope, it might look something like this:


How many wavelengths there are in a second determines the frequency. the frequency also determines the sound's pitch. For example, a standard A note is a frequency of 440.

If you double that frequency to 880, then you get the octave, which is also A. On the guitar, the octave of any given string is located on the 12th fret, where the double dots are. Interestingly, this fret is exactly halfway across the string.

Do you have your guitar handy? Play the low E string. If you listen very closely, you may notice that you can hear not only the E note, but a whole series of tones on top of it. these are called overtones. All of our music is derived from this.

For now, at least, I'll spare you the intricate mathmatical process that goes into all this. When all is said and done, we are left with the 12 notes on the chromatic scale that we talked about in lesson.

When we put 2 of these notes together, we get an interval. Here are the intervals:

unison	two of the same notes
minor 2nd	one half step (fret) away
major 2nd	one whole step (two frets)
minor 3rd	one whole step and one half step
major 3rd	two whole steps
perfect 4th	two wholes, one half
augmented 4th	three wholes
perfect 5th	three wholes, one half
minor 6th	four wholes
major 6th	four wholes one half
minor 7th	five wholes
major 7th	five wholes one half
octave	all 12 frets

These are also names for notes in relation to another, even if not played at the same time. If you play them in a certain order, it creates a scale. This is the major scale:

root, major second, major third, perfect fouth, perfect fifth, major 6th, major 7th

This is the minor scale:

root, major second, minor third, perfect fouth, perfect fifth, minor 6th, minor 7th

Is it making sense? If you're confused about anything, don't be afraid to ask on the forum.