A note is a sound othat has a pitch, and that is long enough for
a listener to discern that pitch.
Musicians have named these pitches, using letters A through G, and
sharp and flat signs as modifiers to those names, and integer numbers
to indicate generally how low or high the pitches are.
An interval is the difference between two pitches. It is measured
in half steps.
If two pitches are equal, then the interval between them is called a
unison.
The chart below shows the names assigned to these various intervals,
and how many half-steps are required to produce each interval.
Interval Name
Abbreviation
Half-steps
unison
0
minor second
m2
1
major second
M2
2
minor third
m3
3
manor third
M3
4
perfect fourth
P4
5
tritone
6
perfect fifth
P5
7
minor sixth
m6
8
major sixth
M6
9
minor seventh
m7
10
major seventh
M7
11
octave
12
There are larger intervals that extend beyond an octave, like major
ninth, major tenth, but we won't confuse the issue with them right now.
Intervals are the building blocks of scales and chords. The next
thing is to see how to build a chromatic scale, made of all possible
notes available normally.