This paper explains the information needed to understand the hardware components that make up the chipset-based audio subsystem in a modern PC. Starting from the Audio Codec 97 (AC97), Intel introduced the Intel High Definition Audio (Intel HD Audio) solution in 2004. This paper also explains the three key types of physical components in an Intel HD Audio solution are the Audio Controller, Audio Link, and Audio Codec, focusing on the audio function group (AFG) and the widgets used to access their functionality. An example of the widgets that are used in a real-world codec is shown.