Your keyfob is a tiny device with a big job -- to keep your car from being stolen. See more car gadget pictures iStockphoto.com /Tom England

­Did you ever notice that it seems you never have to actually put the key into the car door to unlock it anymore? Keyless entry systems -- which use a small radio transmitter built into a keyfob to unlock the doors -- have become standard equipment on almost every new car.

When you push the button on your keyfob, it transmits a signal to the receiver inside your vehicle tuned to receive that particular frequency. This triggers the doors to lock or unlock depending on which button you push. The same technology is used to open your automatic garage door at home.



But when you think about it, you're entrusting the safety and security of your automobile to a very tiny and seemingly simple device. Why is it that your keyfob doesn't unlock the door to a similar model car -- or even a different car? And what's to stop a thief from using the same signal to get into your vehicle?

­It's not often you hear about cars being stolen using this method. The reason: it simply doesn't happen very often. While it's theoretically possible, the technologies used in modern remote entry systems -- like rolling codes and data encryption -- make a theft of this nature pretty difficult to pull off. If a thief wanted to steal your car this way, he or she would have a pretty high-tech mountain to climb.

Next, we'll discuss why you don't necessarily have to worry about someone using your vehicle's keyless entry system to make off with your ride.