The lines are strings and frets
In a typical vertical chord diagram, six vertical lines represent the strings. Read them from left to right as low E, A, D, G, B and high E. This is diagram order; do not assume the left edge of the page is the same as your view while looking down at a guitar.
The horizontal lines represent frets. A heavy line at the top usually marks the nut, so the first space below it is fret 1. A diagram higher up the neck may show a starting fret number instead.
Dots show where to press
A dot on a string, inside a fret space, tells you where to place a fingertip. Press in that space just behind the metal fret, rather than directly on the metal or far back in the space.
Some diagrams include finger numbers: 1 is the index finger, 2 the middle, 3 the ring and 4 the little finger. Finger suggestions help you form a shape but are different from fret numbers.
O means open. X means leave it out.
An O above a string means play it open, without pressing a fret. An X means that string should not sound for that chord. It is not an instruction to press an X-shaped position.
Before strumming, find the lowest string the diagram asks you to play. This matters for chords whose low E or A string is left out.
Read an E-minor example
The E-minor diagram has dots on the A and D strings at fret 2. The low E, G, B and high E strings are open. All six strings are included.
You may also see the compact notation 022000, read from low E to high E. Here, 0 means open and 2 means fret 2. The numbers describe the frets, not which fingers to use.
Turn the map into a check
- Name the strings before placing your fingers.
- Find the required fret space on each string.
- Check any O or X markers.
- Play the included strings one at a time, then together.
Follow the full E-minor exercise to try this on your instrument.