Resistors are two-terminal components used for limiting current, voltage division, and timing applications. Resistors complement ‘active’ components like op-amps, micro-controllers, or integrated circuits for a variety of operations like biasing, filtering, and pulling up I/O lines. Variable resistors can be used to change the properties of a circuit. Current sensing resistors are used to measure the current in a circuit. The unit of resistance is Ohms (Ω).