A device used to convert analog signals into digital form is called an Analog-to-Digital Converter (ADC). This technology samples the analog signal at specific intervals and quantizes it into digital values that can be processed by computers or other digital systems. ADCs are essential in various applications such as audio processing, telecommunications, and data acquisition systems. They enable devices to capture real-world signals (like sound or temperature) in a format suitable for digital processing and analysis, thus bridging the gap between analog and digital communications.