A differential amplifier is an electronic device that amplifies the difference between two input voltage signals while rejecting any signals that are common to both inputs. This makes it particularly useful in applications where noise reduction is essential, such as in audio processing and sensor signal conditioning. The basic configuration of a differential amplifier typically includes four resistors and two transistors, forming a circuit that can effectively amplify small voltage differences. It is a fundamental building block in many electronic systems, including operational amplifiers and instrumentation amplifiers, which are widely used in medical devices and communication systems.