INTERVALS

The distance between notes is known as an interval and is usually measured from the root note.  As was mentioned earlier a major chord is made up from the root, third and fifth note of the major scale.  To be more accurate it is made up from the root, major third and perfect fifth.  Chords, scales and arpeggios are often described using this method. 

Minor 2nd
Major 2nd
Minor 3rd
Major 3rd
Perfect 4th
Augmented 4th / Diminished 5th
Perfect 5th
Minor 6th
Major 6th
Minor 7th
Major 7th
Octave