A voltage reference is a device that provides a stable and precise voltage output, which is essential for various electronic applications. It ensures that circuits operate correctly by maintaining a consistent voltage level, regardless of changes in temperature, load, or supply voltage. This stability is crucial in systems like analog-to-digital converters and operational amplifiers, where accurate voltage levels are necessary for proper functionality. Voltage references can be found in two main types: bandgap references and Zener diodes. Bandgap references use semiconductor properties to create a stable voltage, while Zener diodes rely on the breakdown voltage of a diode. Both types are widely used in electronic devices to enhance performance and reliability.