The purpose of a smart home system is convenient to homeowners, and sometimes police, to unauthorized entry attempts into their homes. When the alarm is triggered, it emits a loud sound designed to frighten away intruders. Also house owner and police center will get phone call alert and SMS alert by mobile. If install the IP camera together that enable to check video of the house anywhere.  Also An optional monitoring system can be tied to your home alarm that alerts a third-party monitoring vendor to contact the appropriate authorities. The home alarm is composed of a central processing unit and remote sensors. 

The central processing unit, or brain box, is the user's interface into the system. It allows users to turn the device on and off, disable or enable certain sections of the home and it automatically contacts optional third- party monitoring vendors. It also communicates with the remote sensors. Most systems have three types of remote sensors. 

The most common remote sensor is the magnetic switch. These are usually found on doors and sometimes windows. They are separated into two parts. The smaller magnet is attached to the door. The larger switch is attached just above it on the door frame. The magnet holds the switch in place. When the door is opened, the magnet moves away. The switch is no longer held in place and the alarm is triggered.

Another common remote sensor is the infrared motion detector. This device detects the movement of objects that emit heat energy. A ball rolling on the floor will not trigger the alarm because the ball does not emit heat. A person does emit heat and will trigger the alarm if he moves. Many infrared motion detectors can be tuned to ignore smaller heat signatures. This can be useful if you have pets.

The third most common remote sensor is the glass sensor. These are commonly placed on windows. They detect the vibrations and sound frequencies of breaking glass. Glass sensors provide extra protection for windows that can be broken and crawled through without opening.

Other devices, such as smoke detectors, flood detectors, carbon monoxide detectors and temperature detectors can also be added to most home alarm systems. These devices can give homeowners and authorities early warnings to environmental threats.