Security is the degree of resistance to, or protection from, harm. It applies to any vulnerable and valuable asset, such as a person, dwelling, community, item, nation, or organization.
As noted by the Institute for Security and Open Methodologies (ISECOM) in the OSSTMM 3, security provides "a form of protection where a separation is created between the assets and the threat." These separations are generically called "controls," and sometimes include changes to the asset or the threat.
Security has two dialogues. Negative dialogue is about danger, risk, threat and etc. Positive dialogue is about opportunities, Interests, profits and etc. Negative dialogue needs military equipment, armies, police. Positive dialogue needs social capital, Education, social interaction.
Perception of security may be poorly mapped to measureable objective security. For example, the fear of earthquakes has been reported to be more common than the fear of slipping on the bathroom floor although the latter kills many more people than the former. Similarly, the perceived effectiveness of security measures is sometimes different from the actual security provided by those measures. The presence of security protections may even be taken for security itself. For example, two computer security programs could be interfering with each other and even cancelling each other's effect, while the owner believes s/he is getting double the protection.
A security alarm is a system designed to detect intrusion – unauthorized entry – into a building or area. Security alarms are used in residential, commercial, industrial, and military properties for protection against burglary (theft) or property damage, as well as personal protection against intruders. Car alarms likewise protect vehicles and their contents. Prisons also use security systems for control of inmates.
Some alarm systems serve a single purpose of burglary protection; combination systems provide both fire and intrusion protection. Intrusion alarm systems may also be combined with closed-circuit television surveillance systems to automatically record the activities of intruders, and may interface to access control systems for electrically locked doors. Systems range from small, self-contained noisemakers, to complicated, multi-area systems with computer monitoring and control.
The most basic alarm consists of one or more sensors to detect intruders, and an alerting device to indicate the intrusion. However, a typical premises security alarm employs the following components: