Intervals on a guitar take on distinctive shapes depending on whether or not the interval cross the boundary between the second and third string, here marked with a red line. This boundary is created due to the fact that there is a Major 3rd between the second and third strings, and a Perfect Fourth between all other strings.
Each yellow gold line represents an interval between two notes. This is exactly what an interval is the distance between one musical note to the next.
Perfect 1st (Unison)
minor 2nd
Major 2nd
minor 3rd
Major 3rd
Perfect 4th
diminished 5th
Perfect 5th
minor 6th
Major 6th
minor 7th
Major 7th
Perfect 8th (octave)
