Most resistor values are specified by its color bands.
Example 1:
Looking at the picture above you can see there are four bands of color. From left to right it reads brown, black, red, gold. Since the color gold gives the tolerance of a resistor, we now know that the value of the resistor reads from left to right; brown(1), black(0), red(2), gold(5%).
First 2 bands specify the absolute value: 10
Third color band specify the number of zeros that follow: 2 zeros
Gold color band specifies the tolerance value of the resistor: 5%
The value of the resistor is: 1000 ohms (+/- 50 ohms) or 1k ohm (+/- 50 ohms)
Example 2:
Looking at the picture above you can see there are four bands of color. From left to right it reads gold, orange, blue, green. Since the color gold gives the tolerance of a resistor, we now know that the value of the resistor reads from right to left; green(5), blue(6), orange(3), gold(5%).
First 2 bands specify the absolute value: 56
Third color band specify the number of zeros that follow: 3 zeros
Gold color band specifies the tolerance value of the resistor: 5%
The value of the resistor is: 56000 ohms (+/- 2800 ohms) or 56k ohms (+/- 2.8k ohms)