How to tune a guitar to standard tuning
From the lowest (6th) string to the highest (1st), standard tuning is E, A, D, G, B, E.
Play each open string and turn the tuning peg until the needle is centered. If the note is flat, tighten the string; if it is sharp, loosen it. Always start slightly below the note and tune up: the string will hold its pitch better.
Alternate tunings
Drop D: the 6th string goes down a whole step to D. A rock and metal staple for one-finger power chords.
Open G and open D: the open strings form a major chord, perfect for slide and blues. DADGAD: an open tuning loved in Celtic and folk music.
Half step down (E♭): every string goes down a semitone, as heard with Jimi Hendrix or Guns N’ Roses.
Why does my guitar go out of tune?
New strings stretch during their first days, so they need frequent retuning. Changes in temperature and humidity matter too. Old strings sound dull and won’t stay in tune: replace them regularly.