Definition & Meaning of "[hold] {one's} tongue"

What is the origin of the idiom "hold one's tongue" and when to use it?

The idiom "hold one's tongue" originates from the idea of physically and literally holding or stopping the tongue to prevent speech. Historically, this phrase has been used to advise or command someone to remain silent, especially in situations where speaking might be inappropriate, unwise, or harmful, meaning refraining from saying something to avoid conflict, maintain decorum, or prevent the spread of unnecessary or harmful information.