The first documented case of car theft was in 1896, only a decade after gas-powered cars were first introduced. From that early era to today, cars have been a natural target for thieves: They are valuable, reasonably easy to resell and they have a built-in getaway system. Some studies claim that a car gets broken into every 20 seconds in the United States alone.


Photo courtesy Directed Electronics
The Sidewinder car-alarm system includes a number of sensors and alarm signals.

In light of this startling statistic, it's not surprising that millions of Americans have invested in expensive alarm systems. Today, it seems like every other car is equipped with sophisticated electronic sensors, blaring sirens and remote-activation systems. These cars are high-security fortresses on wheels!

In this edition of HowStuffWorks, we'll look at modern car alarms to find out what they do and how they do it. It's amazing how elaborate modern car alarms are, but it's even more remarkable that car thieves still find a way to get past them.