An aux adapter is an electronic device that allows you to plug in a device with an aux port into a device that doesn't have an aux port. Most commonly, an aux adapter is used to connect an audio device (like an MP3 player or tablet device) to a car stereo with no Aux port. By plugging in the Aux adapter, you can use the device as a source for music or podcasts for the car stereo system. Aux adapters can come in many different forms like a 3.5mm-to-3.5mm cord, headphone jack adapter, or an RCA-to-3.5mm jack adapter. Aux adapters are a great way to get around not having an Aux port in your device or car stereo.