Top 5 Innovations in Home Security

If you lived in the age of Alexander the Great, your lock might have been a rope with a fancy knot to keep intruders out. Years later, the rope was discarded in favor of a heavy, wooden bar. The bar would block your door in the event that a group of ramrod-carrying men in loincloths tried to force their way into your castle. More intricate mechanical devices like padlocks and pin tumbler locks were later developed. The pin tumbler lock introduced a key into the equation, which quickly became a status symbol. If you owned a key, this broadcast to the masses that you had property to protect. Now, virtually everyone has a key lock of some sort on their home.

Early security systems involved bells on a door or cans tied to a string that made a loud sound when a door was opened. These were effective until someone figured out how easy they were to remove.

The predecessor of the security systems we know today came about when a clever soul tied a pair of wires to the local police station's alarm panel via telephone lines. Ultimately, this system was updated and they became the norm in households everywhere. Today, wireless security systems are popular, easy to install and don't rely on a hard-wired phone line.

Truly an impressive innovation, security cameras took catching the bad guy to a whole new level. Originally they were simply surveillance systems -- cameras attached to a bank of monitors that had to be staffed at all times. They were mainly used by police to monitor public locations. When the video cassette came along, surveillance cameras were adopted by businesses to help control crime. Today, the Internet and wireless devices have reduced the cost of materials and installation. As a result, home security camera systems are no longer considered a luxury.

Early motion detectors that were part of alarm system hardware relied on sound waves to detect changes in an environment. This meant regular household sounds like the swishing of a dishwasher or the ca-chunk of a heater kicking on set it off and caused a lot of false alarms.

Infrared technology eventually replaced the ultrasound, and now it's most commonly found in motion detector floodlights. Motion detectors sense the presence of body heat and reward the intruders with a bright spotlight in their eyes.

In the science fiction movie "Gattaca," Ethan Hawke's character was able to get into a secure area using nothing but a scan of his retina. That technology actually exists today. It's called biometrics. In addition to your eyes, it can scan your fingerprints or recognize your voice. It's a great choice for people with fat bank accounts who harbor government secrets, but for the rest of us, digital door locks offer a cheaper home security option. Digital door locks can be opened with an electronic "smart key" or a remote, or you can open them by typing numbers on a pin pad. These locks are almost impossible to pick.