you play a note, and then play a higher or lower note, the distance between
them is called an interval. It is a 'melodic' interval if the two
notes are played one after the other, or a 'harmonic' interval if they
are played together. The size of an interval is measured by the number
of degrees of a scale it includes, it is always numbered from the
bottom note and that note is considered number one.
RECOGNISING INTERVALS !!!
2nds, 3rds, 6ths and 7ths are
called major intervals
MORE ABOUT INTERVALS :
When a perfect interval is made a semitone larger, it becomes augmented