A primary microphone is a type of microphone that captures sound directly from its source. It is typically used in recording or live performances to capture clear and accurate audio signals, as it is placed close to the sound source, such as a musical instrument or a person speaking into it. The term "primary" refers to the fact that this type of microphone is usually the first step in the chain of capturing and amplifying sound, with any additional microphones used for specific purposes like picking up room ambiance or other effects being considered secondary.