Rock Power Chords

Learning guitar chords

• Mayor chords
• Minor chords
• Diminished chords

A major chord is a chord that has a root, a major third, and a perfect fifth. When a chord comprises only these three notes, it is called a major triad. 
For example, the major triad built on C, called a C major triad, has pitches C–E–G

A minor chord is a chord that has a root, a minor third, and a perfect fifth. When a chord comprises only these three notes, it is called a minor triad.
For example, the minor triad built on A, called an A minor triad, has pitches A–C–E

A diminished triad, also known as the minor flatted fifth, is a triad consisting of two minor thirds above the root. It is a minor triad with a lowered (flattened) fifth. When using chord symbols, it may be indicated by the symbols "dim", "o", "m♭5", or "MI(♭5)". However, in most popular-music chord books, the symbol "dim" and "o" represents a diminished seventh chord (a four-tone chord), which in some modern jazz books and music theory books is represented by the "dim7" or "o7" symbols.
For example, the diminished triad built on B, written as Bo, has pitches B-D-F

Diminished chords are a type of chord that are either played with three notes – a diminished triad – or four notes – a diminished seventh chord.

The diminished seventh chord is a four-note chord (a seventh chord) composed of a root note, together with a minor third, a diminished fifth, and a diminished seventh above the root: (1, ♭3, ♭5, double flat7).
For example, the diminished seventh chord built on B, commonly written as Bo7, has pitches B-D-F-A♭