An interval is the distance between 2 notes. There are 2 different types of intervals. If you play one note after another it is called a melodic interval. If you play 2 notes together it is called a harmonic interval. When you play the same note at the same time you are playing in unison.
Now, using the diagram below I will try to explain intervals. Each fret is 1/2 step. The distance of 2 frets is a whole step. A 1/2 step is also called a minor 2nd (see the diagram below). A whole step is also called a major second. Now here is a chart for you to relate the interval diagram to the chart.
| Name | Distance |
| Unison | none |
| Minor 2nd | 1/2 step |
| Major 2nd | 1 whole step |
| Minor 3rd | 1 whole step and 1/2 step |
| Major 3rd | 2 whole steps |
| Perfect 4th | 2 whole steps and 1/2 step |
| Augmented 4th / Diminished 5th | 3 whole steps |
| Perfect 5th | 3 whole steps and 1/2 step |
| Minor 6th | 4 whole steps |
| Major 6th | 4 whole steps and 1/2 step |
| Minor 7th | 5 whole steps |
| Major 7th | 5 whole steps and 1/2 step |
| Octave | 6 whole steps |
Note: Sometimes the Augmented 4th / Diminished 5th is called the Tritone.
The diagram below shows the intervals for going along one string down the fretboard.
