An AudioNode is a fundamental component of the Web Audio API, which is used to create and manipulate audio in web applications. It represents an audio processing module that can perform various functions, such as generating sound, processing audio data, or controlling audio playback. Each node can be connected to others, forming a flexible audio graph that allows for complex sound manipulation. AudioNodes can be categorized into different types, including AudioBufferSourceNode for playing audio files, GainNode for adjusting volume, and AnalyserNode for visualizing audio data. By connecting these nodes, developers can create rich audio experiences in their applications, enhancing user interaction and engagement.