An auxiliary port (AUX) literally just means an additional audio input method. It is an asynchronous serial port with an interface that allows the auxiliary input of audio signals for: MP3 players. Headphones. Portable music players.

What can you plug into an AUX input?

Use the AUX input to connect audio devices directly to your speaker. Audio devices with a compatible 3.5mm AUX output plug can be connected, like MP3 players, smartphones, and tablets. Insert one end of the AUX cable into the AUX input on the bottom of your speaker.