Final answer:
The fourth band on resistors represents the tolerance of the resistor.
Step-by-step explanation:
The fourth band on resistors represents the tolerance of the resistor. Tolerance refers to the allowable variation in the resistance value of the resistor.
For example, if a resistor has a resistance value of 100 ohms with a tolerance of ±10%, it means that the actual resistance could be anywhere between 90 ohms and 110 ohms.
Other bands on a resistor provide information about the resistance value, the multiplier, and sometimes the temperature coefficient.