Often heard as happier sounding chords, major chords are used in all types of music. The most common open major chords include A, C, D, E and G, all of which can be played by fretting three strings with your fretting hand. For this reason, open major chords are referred to as triads, meaning they are made up of three notes stacked together. The chord starts with the root, followed by the third and the fifth. For example, a C chord is built around a C root note, an E third and G fifth.
Like open major chords, open minor chords can be played by stacking three notes on top of each other. Common open minor chords include A minor, B minor and E minor. Open minor chords are built differently however, as they are made with a root note, a flat third and a fifth. For example, an A minor chord is built with an A root note, a C third and an E fifth.
Diminished triads contain a root note, minor third and diminished fifth. Though diminished triads are used less frequently, they are simple to play and are valuable in teaching music and chord theory to kids. An example of a diminished triad would be a B diminished chord, which is built with a root B note, a D third and an F fifth.
Augmented triads are used a bit more frequently than diminished triads, though less often than major and minor chords, but they are easy to learn and help kids learn basic theory and chord progressions. Augmented triads contain a root note, major third and augmented fifth. For example, a D augmented triad is built using a D root note, an F# third and an A# fifth.