A linear regulator is an electronic device used to maintain a constant output voltage despite variations in input voltage or load conditions. It operates by dissipating excess voltage as heat, ensuring that the output remains stable. This simplicity makes linear regulators popular in low-power applications where noise and ripple are minimal. Linear regulators are often used in power supply circuits for microcontrollers, sensors, and other electronic components. They are favored for their ease of use and low output noise, but they are less efficient than switching regulators when there is a large difference between input and output voltages.