Reference
Two diagram styles show up across these handouts — a short chord diagram for a single voicing, and a tall full-neck diagram for a pattern that runs up the fretboard. Both are always six strings, low E on the left to high e on the right. Here's what every mark on each one means.
Not every chord diagram starts at the nut, though. Here's that same G major triad again, played higher up the neck instead: 5th fret on the D string, 4th on the G string, 3rd on the B string.
Diagrams up the neck like this don't use X's — a string with no dot on it simply isn't part of the shape. An O still shows up occasionally, on the rare shape that includes an open string.
This one needs less explaining — it's really just a picture of the guitar neck, so the same rules already apply: horizontal lines are still frets, vertical lines are still strings, low E still on the left. The numbers along the side mark which real fret each row is. Sometimes you'll see this diagram turned on its side, running left to right instead of top to bottom — same diagram, same rules, just rotated.
Every G, B and D on the neck through the 12th fret — the G major triad, everywhere it occurs. Not a shape to play as one; just here to show the notation.
This page doesn't teach a concept on its own — it's the key for everything else here. Keep it in front the first few times through a new sheet.