Two common types of car alarms are passive and active choices. The passive system is set automatically every time the key comes out of the ignition and all the doors are closed. The active system requires the driver to physically turn it on when passengers have left the vehicle. Passive systems are more securely sound in that the driver does not always have to remember to turn it on every time they leave the car. However, active systems are useful in that if the driver forgets something inside the car, they do not have to deal with the security system going off when they try to get back inside the vehicle.

Engine immobilizers, which are electronic security devices that are placed inside an automobile engine, prevent the whole machine from being hot-wired and stolen. These devices work by keeping the engine from starting unless the key is present. This prevents criminals from being able to manipulate the wires of automobiles and hinders theft.

Another common system is the audible alert, which blasts the horn and flashes the automobile’s lights when the sensors on the vehicle are set off. The sensors’ sensitivity levels can be adjusted to be very sensitive to any slight movements or to only go off when a significant movement is felt. This system is useful because of the ability to adjust the sensors depending on the environment the driver is in and because if someone attempts to break inside, the horn will go off, and the lights will flash. The commotion will attract the eyes of anyone else that is around, and the criminal will most likely be scared off.

With the many recent advancements in technology, companies have been able to develop silent car alarms, which alert the driver through their mobile phone when the ride is being tampered with. When the sensors around the automobile sense movements, the driver will receive a call that suspicious activity is occurring and that someone may be attempting to break into their vehicle. This system allows the driver to call the police when they receive an alert on their cell phone so that the criminal may be caught and arrested.