A Bluetooth transmitter is a device that sends audio signals wirelessly to other Bluetooth-enabled devices, such as headphones, speakers, or smartphones. It connects to audio sources like TVs, computers, or music players, allowing users to enjoy sound without the hassle of wires. These transmitters are particularly useful for older devices that lack built-in Bluetooth capabilities. By plugging the transmitter into the audio output, users can easily stream music or sound to their Bluetooth devices, enhancing their listening experience while maintaining mobility and convenience.