That's the resistor that has to be used with a thermistor.
It's called pull up if it's connected between Arduino pin and 5volt.
It's called pull down when it's connected between pin and ground (your circuit).
Pull up is generally preferred, because there is no v5volt running to sensor or hotplate that can short out to ground. Both ways will work, but the code is different.
Your code seems to be set up for a 10k resistor.
temp = log(10000.0...
Leo..