What is an interval? An interval is the space between one note to another. It can be a space of 2 notes in a melody (notes played one by one) or harmony (notes played simultaneously for example chords). Now let's take a look at this so called intervals.
We have the first, second, third, fourth, fifth, sixth, seventh and octave. You could also include the ninth, tenth, eleventh, etc... but these will be explained later on.
Note: I will now refer to the intervals in numbers.
Since we know the names of the intervals, we now have to know that there are certain differences in them.
We have 3 different type of intervals. Perfect, Consonant and Dissonant.
Perfect intervals are the 1, 4, 5 and 8(octave).
Consonant intervals are the 3 and 6.
Dissonant intervals are the 2 and 7.
Now we need to look at some definitions for these intervals. Consonant and dissonant intervals can be minor or major, for example; m2, M2, m3, M3, etc. Perfect intervals are, as the name already says, perfect. They have no minor nor major.
You can still diminish and augment this intervals. This can be very confusing but bare with me. If we see all the different interval names that a second has, from lowest to highest interval, it would look like this; dim2, m2, M2, aug2. This also goes with all the other intervals that are not perfect. Perfect intervals would be for example; dim1, P1, aug1. This as said goes for all the perfect intervals.
Here is the complete chart of the intervals between the 1 (first) and the 8 (octave).
first: dim1, P1, aug1.
second: dim2, m2, M2, aug2.
third: dim3, m3, M3, aug3.
fourth: dim4, P4, aug4.
fifth: dim5, P5, aug5.
sixth: dim6, m6, M6, aug6.
seventh: dim7, m7, M7, aug7.
octave: dim8, P8, aug8.
Let's do the same with with notes beginning with C, for a better explanation.
Note: b means flat, # means sharp.
first: Cb, C, C#.
second: Dbb, Db, D, D#, D##.
third: Ebb, Eb, E, E#, E##.
fourth: Fb, F, F#.
fifth: Gb, G, G#.
sixth: Abb, Ab, A, A#, A##.
seventh: Bbb, Bb, B, B#, B##.
octave: Cb, C, C#.
Now, there is something we need to know. It is called enharmonic equivalent. If you look closely and think it threw, you might notice something. C# and Db are the same notes. This also happens with other notes. This is called enharmonic equivalent. This is very important to know when building scales and chords. You can never use the same note twice in a scale. For example if the second is a F# you are not allowed to say that it is a Gb, because the Gb would be a diminished third and would have nothing to do with the second. This might be really confusing but it is important to know or else you can get in some real trouble when composing or writing scales and chords.
I hope this lesson was understandable. If there are any questions, please send me a message.