What is the note at the 3rd fret of the A string?

The note at the 3rd fret of the A string is C. To understand this, it's important to know that each fret on a guitar raises the pitch of the note by a half step. The A string, when played open, is tuned to A.

By moving to the 1st fret, the note becomes A# (or Bb), and at the 2nd fret, it becomes B. When you reach the 3rd fret, the note is raised another half step, giving you C.

So, the process involves counting up the half steps from the open string note. This understanding of the fretboard and note relationships is fundamental for playing chords, scales, and melodies effectively.