A remote starter is a radio controlled device, which is installed in a vehicle by the factory or an aftermarket installer to preheat or cool the vehicle before the owner gets into it. Once activated, by pushing a button on your keychain remote, it starts the vehicle automatically for a predetermined time. Different models have keyless entry as well. Most newer vehicles need some kind of bypass module to bypass the factory anti-theft system, so the vehicle can be started without the ignition key in the ignition, this is bypassed only to start the vehicle, which after it is running returns to its original state. Having a remote starter installed in your vehicle will not void your factory warranty when installed properly.