Tuning words, simply.

A plucked string swings back and forth many times a second. Hz (hertz) counts those swings. The thick low E string of a guitar swings about 82.4 times a second, the A string 110 times. Tighten a string and it swings faster: the number goes up and the note goes up.

▶ Low E, then A (82.4 → 110 Hz)

Play the open A string (110 Hz), then the same string at fret 12: 220 Hz. Twice the speed, and it still sounds like A, only higher. That is an octave. Notes repeat every octave, which is why there are only twelve note names.

▶ A, then the A an octave up

Move one fret up and the note rises a semitone, also called a half step. Twelve semitones make an octave, so twelve frets take a string from E to the next E.

When a tab says "tune down a half step", every string goes down one fret's worth: E becomes E♭, A becomes A♭, and so on. That is E♭ Standard.

▶ A semitone: E, then F ▶ Low E, then low E♭

Two semitones make a tone, or whole step. "Tune down a whole step" moves every string two frets lower: E A D G B E becomes D G C F A D, which is D Standard. "A step and a half" is three semitones: C♯ Standard.

TuneLit's tuner counts in half steps: −1 is E♭ Standard, −2 is D Standard.

▶ A tone: E, then F♯ ▶ Low E, then low D

Between two frets there are 100 cents. A string that is 50 cents flat sits exactly halfway between two notes. Cents are what the tuner's meter shows, and what the band pages mean by "+6 ¢": the record is 6 hundredths of a semitone higher than A 440. TuneLit sets the tuner to match it, so your guitar and the record agree.

Listen: the same A, then a little higher. Then both together, as two strings: a few cents apart they beat, a slow wobble that stops when they agree.

▶ A, then +5 ¢ ▶ A, then +10 ¢ ▶ A, then +20 ¢ ▶ A, then +50 ¢ ▶ A, then +100 ¢ (B♭)

▶ Together, in tune ▶ Together, 5 ¢ apart ▶ Together, 20 ¢ apart

The A above middle C is tuned to 440 Hz almost everywhere, and every other note is worked out from it. That is the "A 440" on the tuner's chip. Change it and all notes move together: at A 432 everything sits about 32 cents lower, at A 442 about 8 cents higher. Near 440, one hertz is about 4 cents.

Many records are not at A 440: tape machines ran a little fast or slow, and bands tuned to each other by ear. Pantera's Vulgar Display of Power sits near A 426, about 57 cents flat. A band page's Tune button sets the A, or the cents, so you match the record.

▶ A 440, then A 432 ▶ A 440, then A 426

Sharp means too high, flat means too low. On the tuner, a flat string shows left of center (tighten it), a sharp one right of center (loosen it).

In note names, ♯ raises a note a semitone and ♭ lowers it: F♯ is one fret above F, E♭ one fret below E. C♯ and D♭ are the same fret, two names for one note.

• Standard. E A D G B E. "E♭ Standard" or "D Standard" is the same pattern moved down, so every chord shape still works.
• Drop. Only the lowest string goes down a whole step: Drop D is D A D G B E. One finger across the three low strings plays a power chord.
• Open. The open strings make a chord: Open G is D G D G B D. Great with a slide.

A capo clamps all strings at one fret, so every open string sounds that many semitones higher: capo on fret 2 turns E A D G B E into F♯ B E A C♯ F♯.

It also works backwards, as a tuning trick: put the capo on fret 2, tune to E Standard as usual, then take it off. Every string is now a whole step lower: D Standard. Each tuning page shows the trick for its own tuning.