Anyone who’s watched the local news, a TED Talk, a Broadway show, or a YouTube interview has seen a lavalier microphone. They’re tiny, they hide well, and they let the speaker walk around freely while staying mic’d up.
A lavalier microphone — also called a lapel mic, a body mic, or just a “lav” — is a tiny condenser microphone meant to be clipped to a shirt or jacket near the speaker’s collar. It connects either by cable or, more commonly today, to a wireless transmitter clipped to a belt or pocket.