A hot mic, sometimes referred to as an open microphone or (in aviation) a stuck mic, is in general an apparent error in which a microphone is switched on or remains on, especially without the speaker realizing.

A special case of hot mic is the microphone gaffe, in which the microphone is actively collecting and transmitting sound gathered near a subject who is unaware that their remarks are being transmitted and recorded, allowing unintended listeners to hear parts of conversations not intended for public consumption. Such errors usually involve live broadcasting in radio or television, and sometimes material is recorded and played back via media outlets. Such events can cause embarrassment for the person or organization involved, sometimes resulting in serious confrontations and employment termination.