Happy Birthday by Stevie Wonder is in C at 100 beats per minute and runs 4:19 across 52 bars. It uses 14 chords — C, F, Bb, Eb, Am, Em7, G, Dm7, 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? Happy Birthday guitar melody tab.