Music Theory for Electronic Music Producers: The producers guide to harmony, chord progressions, and song structure in the MIDI grid

Now that we have the root at the end of the melody, we are much more comfortable with it. We can now say that the melody has "resolved."
Do my melodies always need to resolve with the root note? No! Many melodies don't. If you want your melody to sound nice and predictable, make sure it starts and ends with the root. But if you want something other than that, it is perfectly ok to not start or end with a root. Remember that you are the producer and you can do whatever sounds best to you.

The root note has another property as well: the root is "home". It always feels like a good place to end a melody. If you are writing something and want it to feel like it's over, go to the root. That will feel like we've returned back to where we started

The root is the note that the key is named after

To find the 5th, just count up five white notes

You can change a 3rd from major to minor, but you can't change a 5th. It is perfect

To find the Perfect 5th of a note, you can count up five notes from another note staying in key. The key is important here, because if you count up five notes from any other note, you should land on a 5th of the original note, but not necessarily a perfect 5th

If you have a single note, but you want it to sound stronger, meatier, and more forceful, try putting a fifth on it

Whenever you have a riff, pattern, or chord that you want to make "thicker", add an octave to it

Octaves always sound good

There are 100 cents in a semitone