Onstar is an in car telematics system that is often and mostly used by General Motors or GM. It can be used for many purposes including navigation system and alarm systems.
Navigation by way of Turn by turn. You press the blue onstar button which takes you to a telephone assistant and you tell them what yould would like. Give them an address and in many GM vehicles, they beam directions down and can be displayed in your car's radio display system.
It can be an alarm system because if your car is stolen, broken into, or even if you lock your keys in the car, you call onstar and report what happened. They will unlock the door for you!If you get into an accident, they call you and ask if you require assistance. If you do, they call the ambulance, police, ect. For a stolen car, they track it for police to follow!
So yup, thats onstar!