Every position on the guitar is a single piano note. Each fret raises the pitch by one semitone (half step) — the distance between two adjacent piano keys. Click any fret to light up its key on the piano, or click a piano key to see every place that note lives on the neck. Sound is on — you'll hear the guitar pluck and the matching piano tone are the exact same pitch.
Fretboard — low E (6th) at top by default
Piano
Common Beginner Chords — click a chord to strum it and light up its notes on the fretboard & piano
How to read a diagram: the thick bar at the top is the nut (the very top of the neck). Each column is a string, low E on the left to high E on the right. Dots show where to press; the number inside is the suggested finger (1 index · 2 middle · 3 ring · 4 pinky). O above a string means play it open; ✕ means don't play that string. These are standard-tuning shapes, so switch the tuning back to Standard to see them mirrored on the fretboard above.