Guitar chords in the key of C major

The seven chords of C major are C, Dm, Em, F, G, Am, Bdim. Each one has a job in the key, and each tends towards particular chords next.

• C, the tonic of C major. Usually goes to F or G: the first move away from home, and the one that does not raise the stakes.
• Dm, the supertonic of C major. Usually goes to G: roots falling a fifth, the strongest root motion the key has.
• Em, the mediant of C major. Usually goes to Am: roots falling a fifth, and vi is where iii most often lands.
• F, the subdominant of C major. Usually goes to G: subdominant into dominant: the standard approach to a cadence.
• G, the dominant of C major. Usually goes to C: the tritone resolves: the leading tone rises, the seventh falls, and the phrase is over.
• Am, the submediant of C major. Usually goes to Dm or G: roots falling a fifth, straight into the standard approach to V.
• Bdim, the leading-tone chord of C major. Usually goes to C: it is V7 without its root, so it wants the tonic just as badly.

Where a chord tends to go follows Walter Piston’s table of usual root progressions in Harmony (W. W. Norton); see the sources.