Often guitarists will have questions about music theory and this post will give you a basic understanding of the way that chords are built.

First off, you might ask where chords came from. The short answer is that 800 years ago monks would sing tunes in churches. Eventually someone decided that things would be more interesting if two or more different notes were sung at the same time. By the late 17th century there was some consensus regarding note combinations that were most desirable. Those combinations were made into a system where notes are “stacked” on top of other notes in their scale.

Notes that are derived from particular scales are arranged into what are known as “Keys”. In music, these can be thought of as families of chords that have some intrinsic connection. As you look at the examples here, notice that when chords are formed from scale degrees, the sharps or flats in the scale are always included in the chords as well. This creates a congruity of sound that most people find pleasing.

For example, imagine seeing two guitarists jamming together. One of them plays a CM chord for several beats while the other plays a couple of “licks” that seem to fit. How did the person playing lead know what to play? Maybe they just “played by ear”. That is possible, but guess what? if you were to look at the actual notes played in the solo passage, you would almost certainly find that they were emphasizing at least one or more notes in the CM chord. (C, E, G.)

Of course lead guitar playing is far more complex than that. There are a million exceptions to the rules of music theory and many fun and interesting ways to break and manipulate them, but the heart of the matter is that if there is a kind of musical agreement between the notes in a lead passage and the chords underneath (or above) you’ll get more fans than if they clash.

In the beginner phase of lead guitar playing you’ll want to get accustomed to an awareness of the notes within the chord progression. I often begin students with a scale and have them pause as they play notes that seem to “fit” with the chords playing in the background. After a student is able to discern which notes “agree” with the chords in the rhythm part, then they are ready to experiment with various maneuvering between the chord tones. For the most part, if the scale and the chords have the same common tones, it is difficult to do something that sounds terrible.

Before we look at the key of CM you’ll want to understand the differences in Major, minor, and diminished chords. In a Major chord, the distance from the root (the bottom note in these examples) to the third (the middle note) is 4 frets, while the distance from the third to the fifth (the top note) is 3 frets. In a minor chord the distance from the root to the third is 3 frets, and the distance from third to fifth is 4 frets. In a diminished chord there is a distance of 3 frets from the root to the third and 3 frets from the third to the fifth.