Click hereIntervals: Let's talk relationship
The word interval has to do with the distance between two notes. For example:
If we count off the distance between the two notes, we get the interval's name:
And so on. Notice how we include the first and last notes in our tally.
For the time being, we'll ignore the black notes (the sharps and flats). That's because we'll be playing "in the key of C," which basically means we're sticking to the white keys.