The keypad. It has two functions. Firstly, it initiates security commands, and secondly, it monitors the status of the security system. There are two parts to the keypad. The alphanumeric board and the LED display. Usually the keypad is installed near the front door so that the owner can easily arm or disarm the system as he enters and leaves the house. The majority of keypads will have a panic switch so that the alarm can be activated in case of emergency. Most of them will also have a bypass function. This allows the homeowner to bypass the system when necessary.

The sensors. These protect the perimeter and the open spaces in the home. The sensors that are commonly used are magnetic door switches, window movement detectors and window acoustical detectors. They will trigger the alarm if there is any unauthorized movement or sound. You can also install space protection sensors inside the rooms and hallways to detect movement inside the home when there shouldn't be.

The door switches. There are two components to the door switches. The switch and the magnet. The switch is sensitive to the magnetic field and is mounted on a fixed frame. The magnet is mounted on the door near the switch. If the door is opened and the alarm is on, the magnet moves away from the switch, opening the switch and thus activating the alarm.

The window detectors. These detectors are on the windows to sense any movement, or the sound of breaking glass. Either of these will activate the alarm, so that a home cannot be entered by breaking into a window.

Motion detectors. These are designed to detect any changes in infrared energy, so that if an intruder enters the space, they will set off the alarm. They can be standard or pet friendly, or they can be for outdoors, which is considered harsh environment.

The security panels. This is the brain of the home security system. Power is supplied to the system, the sensors are monitored, the programs are operated and the telephone lines connected via these panels.

The cameras. Video cameras that capture and transmit images to the monitors that may be important in picturing intruders.

The monitors. These display the images captured by the video cameras. The cameras are connected to the monitors via coaxial cable.

The switchers. Switchers are used to process the images captured by the cameras. In large systems with a number of cameras, the operator can switch cameras to monitor different areas of the property.