Every note, every string — until you stop counting frets.
Most players who "know the fretboard" didn't memorize 78 separate dots. They learned a few patterns, then drilled recall until it was instant. The path follows that order:
Each CAGED shape has a root on a known string: E and G shapes on the 6th string, C and A shapes on the 5th, D shape on the 4th. Once you know those strings, you can name the key of any shape you're holding just by reading its root. You can also start a chord in any key by finding the root first. In any key, the shapes connect up the neck in order: C → A → G → E → D → C…
Name it: a fret lights up and you tap its note name.
Find it: you're given a note and a string, and you tap the fret.
Note hunt: tap every place a note appears up to fret 12.
CAGED key: a chord shape appears with its roots in orange. Name the key.
CAGED root: you're given a key and a shape. Tap where its root goes.
Progress is saved on this device only. On iPhone: open the page in Safari, tap Share → Add to Home Screen to use it like an app.