Tutorials/Arduino Projects/Additional Info/What Is a Resistor
How to read a resistor
The color bands on a resistor allow you to determine the resistance of the resistor. The first band determines the first digit of the resistance. The second resistor specifies the second digit. The third digit is the multiplier. So you take the first and second digit, say 47, and you take the multiplier, and multiply the number by the multiplier.
The forth band is for the tolerance. The tolerance is the range of valid resistances for that resistor. This is included to specify the maximum variations from manufacturing.