Scruffy

I've read and read about all I can find on resistors and yet I'm still confused about one thing - does a resistor in series affect just the voltage or both the voltage and current? I drew a simple circuit showing the input voltage as 12VDC, with one resistor in series and then the output. What I really want to know is how the resistor in this circuit will affect the voltage and the current at the output. Thank you.