The strings of a guitar are named for the notes they produce when played “open” (in other words, when a string is not being pressed down on a fret). In standard tuning, the open string notes from low to high are E, A, D, G, B, and E. When you place your finger behind a fret, it raises the pitch by one note per fret. For example, pressing down on the first fret on the E string produces an F note.