That’s When I Knew by Alicia Keys is in G at 120 beats per minute and runs 3:30 across 100 bars. It uses 19 chords — N.C., G, D, Csus2, Am, D7, G7, C, and a few more. The chord diagram changes as the song plays and the words light up as they are sung, so you can strum and sing along without reading ahead.
Want the melody line note by note? That’s When I Knew guitar melody tab.