Answer:
Runs smoother than any rhyme, loves to fall but cannot climb!
What is often returned, but never borrowed/
What must be in the oven yet can not be baked? Grows in the heat yet shuns the light of day? What sinks in water but rises with air? Looks like skin but is fine as hair?
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
No matter how little or how much you use me, you change me every month.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.