What is the note located at the G (3rd) string 4th fret?

The G string on a guitar is tuned to the note G at the open string position. As you move up the fretboard, each fret raises the pitch by a half step (or semitone). Therefore, the first fret on the G string plays G#, the second fret plays A, the third fret plays A#, and, finally, the fourth fret plays B.

This consistent pattern of raising the pitch by half steps allows for straightforward navigation of the fretboard. When playing the G string and you press down on the fourth fret, you transform the G into B, confirming that the note at that position is indeed B. Understanding this pattern of half steps is crucial for mastering the fretboard and identifying notes accurately.