The resistor's resistance  limits the flow of electrons  through a circuit.          Resistor units   The electrical resistance of a resistor is measured in  ohms .     Schematic symbol   All resistors have  two terminals , one connection on each end of the resistor. When modeled on a schematic, a resistor will show up as one of these two symbols              Resistor color code chart   The chart below shows how to determine the resistance and tolerance for resistors. The table can also be used to specify the color of the bands when the values are known. An  automatic resistor calculator  can be used to quickly find the resistor values.