On the 11th fret of the 3rd string, what chord is played?

On the 11th fret of the 3rd string (the G string), you are playing the note D. When you play this note and consider the context of chords that could incorporate this note, the chord that fits is F major.

In an F major chord, the notes are F, A, and C. When you incorporate the 11th fret on the 3rd string, you’re effectively playing a D, which is the fifth note in the scale of F major. D creates a smooth transition and serves as a common tone that harmonically supports the F major chord within its characteristic sound.

Furthermore, understanding how chords are built on the fretboard allows players to see that if you derive the chord from different scale degrees, you can build various chords from root notes across the fretboard. In this case, the 11th fret provides a critical tone for the F major chord structure.