A Successive Approximation ADC (Analog-to-Digital Converter) is a type of converter that digitizes an analog signal by using a binary search algorithm. It compares the input voltage to a reference voltage and adjusts its output bit by bit, starting from the most significant bit. This process continues until the output matches the input signal, allowing for precise digital representation. This method is efficient and commonly used in applications requiring moderate speed and resolution, such as in microcontrollers and digital signal processing. The successive approximation register (SAR) is a key component that facilitates this iterative comparison process, ensuring accurate conversions.