The major 2nd on the guitar
2 semitones · M2 · C → D
Its character, in the app's words: dialogue; an octave wider (M9), horizon: the movement opens up.
The shapes on the neck
- On the same string: 2 frets up.
- On the next string, towards the 1st: 3 frets back; 2 frets back when you cross from the G string to the B string, which are tuned a major 3rd apart instead of a 4th.
- Turned upside down it becomes a minor 7th: 2 + 10 = 12 semitones.
The root is the C on the A string, 3rd fret; the other circles are the same note, D, wherever it sits between frets 0 and 12. The 1st string (high e) is at the top, as in the app. The root is filled.
Open it in the app: 2. Intervals
The other intervals