The keys guitarists use

On a piano every key is roughly equally hard. On the guitar some keys are far easier than others, because their chords fall on the open shapes you already know. That is why guitar music is so often in G, C, D, A and E, and in their relative minors, E minor and A minor.

Here are the five, with the chords you have learned. Each row ends with the key's diminished chord for completeness; songs rarely use it.

Open chords: G, C, D, Em and Am, plus Bm as a barre or the small Bm. The friendliest key on the guitar, and the most common in folk and acoustic music.

Open chords: C, G, Am, Dm and Em, plus F, the only hard one, which the small F covers.

Open chords: D, G, A and Em, with Bm and F#m as barre chords. Bright and ringing, and very common in acoustic pop.

A, D and E are open chords; Bm and F#m are barre chords, and the small Bm works too. A favourite for rock and country.

E and A are open chords; B, C#m and F#m are barre chords. E is the natural home key of rock guitar, because the lowest open string is E. Use B7 when the full B is too much.

A song in a minor key uses the same chords as its relative major, but treats the minor chord as home.

• E minor shares its chords with G major: Em, G, Am, C, D, Bm.
• A minor shares its chords with C major: Am, C, Dm, F, G, Em.

So when a song keeps returning to Em, think "the chords of G", and when it keeps returning to Am, think "the chords of C".