A passive speaker is a type of speaker that does not have a built-in amplifier or power source. It is designed to be powered by an external amplifier or receiver, which sends an audio signal through speaker cables to the passive speaker. The passive speaker converts the electrical signal into sound waves that can be heard. Passive speakers are commonly used in home audio systems, professional sound systems, and public address systems. They are generally less expensive than active speakers, which have a built-in amplifier and are self-powered.