An audio adapter is a device that allows different audio equipment to connect and communicate with each other. It can convert signals from one format to another, enabling devices like headphones, speakers, and microphones to work together. For example, a 3.5mm audio adapter can connect a standard headphone jack to a USB port. These adapters come in various types, including Bluetooth adapters for wireless connections and HDMI audio extractors for video devices. They are essential for ensuring compatibility between modern gadgets and older audio equipment, making it easier to enjoy music and sound across different platforms.