Resistors, color code

Resistors are a little electrical components used to distribute properly the voltages and currents flowing through the circuit.
Resistors have some color code, which I will you explain what mean each:

As the picture show, there's a resistor of 4 bands in which there are 4 color code, that means:

-First band: is the first number of the value of the resistence.

-Second band: is the second number of the value of the resistence.

-Third band: represents the number of zeros to be added.

-Fourth band: is the tolerance value of the resistor.

In this table, you can see the value of the color code in a resistor:

In the case of the resistor showed before, will see how to now the resistance value.

The resistor has a brown, red, orange and gold band. This value resistence will be 12000 ohms with 5% tolerance. According to the table, brown color reperesents the "1", the red "2" and orange means that it adds three zeros.