A standard for connecting phones to cars. With MirrorLink, the driver can use a limited set of apps on their phone via the car's dashboard touch screen and/or steering wheel buttons.
The phone displays its interface (or a special interface designed for car use) via the car's screen instead of the phone's screen. The phone is operated via controls in the car rather than on the phone.
MirrorLink also connects the phone to the car's audio system, and versions 1.1 and greater allow phone apps to access certain automotive data from the car.
The standard is actually a group of standards and certifications. It uses USB and Bluetooth to connect the phone to the car, and can also use Wi-Fi.
It also makes use of the UPnP, VNC, and RTP technology standards. Cars, phones, and applications can all be certified for MirrorLink.
MirrorLink was intended to provide functionality similar to Apple's CarPlay and Google's Android Auto. CarPlay and Android Auto became popular while MirrorLink did not.