There are few different types of surveillance cameras like outdoor surveillance cameras that are kept in the streets which are used to track traffic violators and other anti social activities. Domestic cameras which are positioned inside the homes but facing towards the periphery to keep a watch on home intruders and thieves. There are also few nest cameras which can be kept within the home or store to monitor activities of workers or nannies. In the market we can find many more such cameras which are specific to purpose. Door and window sensors are also another key invention in home safety and security. These work on the basic principle of infrared, that is when a door or a window is opened and the infrared sensor is cut without prior intimation to the system, the security alarm goes off and alerts the concerned party of an abnormality in situation. This is very useful when people fear of break ins via windows and doors in the house. These security system can also be combined with other sensors like motion sensor and fire and smoke alarm sensor, finger print recognition, doorbell view camera etc. these security system can further be programmed to contact the police department and your personal guardian immediately in case of an emergency at home. The doorbell camera allows you to see who is at the front door before opening the door to welcoming them. This feature is also now available with newer version to capture the image from the camera in case of a suspicious person and later send the image to the concerned higher official.