Once open chords feel comfortable, movable chord forms unlock the entire fretboard. A barre chord is created when your index finger presses flat across all — or several — strings at a single fret, effectively becoming a movable "nut." The remaining fingers then form a familiar chord shape behind the barre. Because only the fret position changes, the same shape produces a different chord name as you slide it up and down the neck.
The two classic movable shapes come from E and A open chords. The E-shape barre chord lays the index finger flat across all six strings at the target fret, then places the middle, ring, and pinky on the A, D, and G strings in the classic E major pattern. The root note of this shape sits on the 6th string under the barring finger; for example, barring the 3rd fret with an E shape produces a G major chord. To turn an E-shape major into a minor, drop the barre at the chosen fret and place your ring finger on the A string plus your pinky on the D string, each two frets above the barre. Barring the 1st fret gives F minor. To convert an E-shape major barre into a dominant 7th barre chord, simply lift your pinky off the D string; this opens the ♭7 interval on that string. For the A-shape barre, the same idea applies — bar across all strings, form an A major shape on the higher frets, but the root note now lives on the 5th string. Barring the 3rd fret of the A shape, for example, gives you a C major chord. Cleanly fretting these chords requires placing your index close to (not on top of) the fret wire, using the bony edge of the finger, and keeping the thumb centered behind the neck.
Power chords strip harmony down even further to produce the chunky sound heard across rock and punk. A power chord contains only the root and the fifth — no third — making it neither major nor minor. The simplest two-note version places the index finger on the desired fret of a low string for the root and the ring finger two frets higher on the next string for the fifth; for instance, index on the 5th fret of the low E and ring on the 7th fret of the A string gives you an A5. A three-note version adds the octave of the root by placing the pinky two frets up on the next string over (same fret as the ring finger). The lack of a third is exactly why power chords work so well with distortion — the interval that creates dissonance when overdriven is missing entirely, and the simple voicing cuts cleanly through a loud mix. They can be played on any adjacent string pair (6-5, 5-4, 4-3) using a two-fret spacing, but a crucial detail: between the G (3rd) and B (2nd) strings the standard guitar tuning changes, so the fifth must be placed three frets up instead of two.