A resistor is a passive two-terminal electronic component which is used to control voltage by restricting the flow of current in a circuit. Resistors may also protect sensitive electrical components from exploding or blowing due to excessive voltage. Higher resistance means that there will be less current in a circuit. Resistors may either look microchips, or they may be a wire with a small, bead-like colored cylinder of resisting material around it. They are common elements of electronic circuits and electrical networks and are found in almost all electronic equipment. They can be implemented within integrated circuits (microchips), especially in analog devices, and also may be integrated into printed and hybrid circuits.

Resistors can be joined in different combinations in order to complete a circuit. They may be linked in a series, where the resistors are connected on after the other, or that may be parallel, where the resistors are connected over one another. When linked in a series, the current through all of the resistors will be the same, but the voltage across each one will be in proportion to its resistance. When in a parallel configuration, resistors are all subject to the same voltage, but the currents through each one will increase.

There are many varieties of resistors available. Each has a different rating to indicate its resistance to electricity. If a resistor is met with too much power, it may break or its function may become erratic. The bead-like style of resistor has a series of colored bands around it to indicate its rating. Other types of larger resistors are marked numerically, however most modern resistors are so small that marking them is impractical. A resistor’s color may also indicate its rating.

Resistors may be made out of many different materials. In the past, resistors were made from solid carbon, but this type is rare now because it did not fare well with air moisture and can be too expensive to make. Many modern resistors do still utilize carbon as a film. Other modern resistors are made from metal or wire. Newer resistors are also much better at handling air moisture and high heat from electricity. In a properly designed circuit, the failure rate of resistors is much lower than that of other electronic components like electrolyte capacitors and semiconductors. Resistors most often become damaged due to overheating when they receive too much power. This problem can be avoided by ensuring that the resistor is chosen and installed properly.