An “interval” in music is simply distance between two tones. Just like inches, feet, yards, and meters describe distance in physical spaces, intervals like “half steps” and “whole steps” describe distance in music.
“Half steps” are from key to key with no keys in between,
“Whole steps” always skip a key with ONE key( regardless if its a black key or a white note in between.
Examples of an Half Step is thee movement form B to C, F to F#, E to F, C to Db
Examples of Whole step is the movement from C to D, F to G, E to F#, B to C#
There are two basic types of intervals, Harmonic and Melodic.
An Harmonic Interval is when two notes are sounded simultaneously (just like playing two notes together)
A Melodic interval is when two notes are sounded one after the other.
When measuring intervals, it is always measured from the lower note to the higher note.
In addition to having a number, each interval will also have a quality of perfect, major, minor, diminished or augmented. In order to understand these qualities, we will look at the C Major because its the least complicated although it can be applied to all keys.
The Perfect Intervals comprises the 4ths, 5ths and octaves. In classical music, the symbol for a perfect interval is “P”. So the intervals, when written on sheet will be.
Feel free to drop your questions or comments.