Standard guitar tuning from the thickest string to the thinnest is E-A-D-G-B-E, easily memorized with the phrase "Eddie Ate Dynamite Good Bye Eddie." Most adjacent strings are tuned a perfect fourth apart, but the interval between the G (3rd) and B (2nd) strings is a major third — an irregularity that affects every chord, scale, and arpeggio on the instrument. Knowing the open-string names is fundamental because the same two E notes (low and high) are two octaves apart, and they anchor how you read chord roots.
Several alternate tunings open up new sonic landscapes. Drop D lowers just the 6th string from E to D, giving D-A-D-G-B-E; this enables full-sounding power chords with a single finger across the bottom three strings and is popular in rock and metal. Open G tuning is D-G-D-G-B-D — strumming all six open strings produces a G major chord, famously used by Keith Richards. Open D tuning (D-A-D-F♯-A-D) likewise yields an open D major chord when all strings are played open, ideal for slide guitar. DADGAD (D-A-D-G-A-D) creates a modal, Celtic sound that produces a Dsus4 chord when strummed open, used by Pierre Bensusan and Jimmy Page. To tune by ear using the 5th-fret method, play the 5th fret of each string and match it against the open string below it — except between G and B, where you use the 4th fret of the G to match the B. Clip-on chromatic tuners, which detect all twelve chromatic notes, are especially valuable for alternate tunings and noisy environments.
Navigating the fretboard relies on a few key landmarks. On the low E string, the natural notes from open to the 12th fret are E, F (1st fret), G (3rd), A (5th), B (7th), C (8th), D (10th), and E (12th, an octave above open). Note that natural half steps occur between E-F and B-C — there is no sharp or flat between those notes. On the A string, landmark frets are A (open), C (3rd), D (5th), E (7th), and A (12th). On the G string, the same pattern gives G (open), C (5th), D (7th), and G (12th). Octave shapes make it easier to find the same note in different positions: a note on the 6th string has its octave two strings over and two frets up on the 4th string, and the same relationship connects the 5th string to the 3rd. The 12th fret is the midpoint of the vibrating string and produces a note one octave higher than the open string — it is why the 12th fret is marked with double dots as a visual reference.
A capo is a clamp placed on the neck at a chosen fret that shortens all vibrating strings uniformly, raising the pitch and effectively transposing the guitar. Placing it on the 2nd fret raises every sound by two half steps, so a G-shape chord sounds as A, a C shape as D, and a D shape as E. With a capo on the 3rd fret, a G-C-D progression actually sounds as B♭-E♭-F. The capo is the tool of choice when you want the bright, ringing open-string character that barre chords cannot provide, and it is also faster than rewriting chord shapes to change keys between songs. A common application: place the capo on the 2nd fret and play G, C, and D shapes to perform in the key of A, taking advantage of the natural resonance of G-family open chords.