The AnalyserNode is a part of the Web Audio API, which allows developers to analyze audio data in real-time. It provides features to visualize audio signals, such as frequency and time domain representations, making it useful for applications like music visualizers and audio effects. By connecting an AnalyserNode to an audio source, developers can access detailed information about the audio being played. This node can extract data like frequency levels and waveform shapes, enabling users to create interactive audio experiences and monitor sound characteristics effectively.