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