A linear regulator is an electronic device that maintains a constant output voltage despite variations in input voltage or load conditions. It operates by dissipating excess voltage as heat, which allows it to provide a stable power supply for sensitive electronic components. Linear regulators are commonly used in applications where low noise and simplicity are essential. These regulators are typically less efficient than switching regulators, especially when there is a significant difference between input and output voltages. However, their straightforward design and minimal external components make them a popular choice for low-power applications, such as in battery chargers and microcontroller circuits.