All the notes so far studied, as summarized in the following diagram, are in the open position. The open position consists of the open string notes and the notes on the first three frets.
By playing through the notes you will notice that B to C and E to F are only one fret apart (this distance is called a semitone), whereas all other notes are two frets apart (called a tone). The distance between notes of the musical alphabet can be set out as such:
It is essential for you to remember this pattern of notes.