Security is the condition of being protected against danger or loss.

In the general sense, security is a concept similar to safety.

The nuance between security and safety is an added emphasis on being protected from dangers that originate from outside. 

Individuals or actions that encroach upon the condition of protection are responsible for the breach of security.

The word "security" in general usage is synonymous with "safety," but as a technical term "security" means that something not only is secure but that it has been secured.

Security has to be compared and contrasted with other related concepts: Safety, continuity, reliability.

The key difference between security and reliability is that security must take into account the actions of active malicious agents attempting to cause destruction.

It is very often true that people's perception of security is not directly related to actual security.

For example, a fear of flying is much more common than a fear of driving; however, driving is generally a much more dangerous form of transport.

The tool may be mistaken for the effect, for example when multiple computer security programs interfere with each other, so the user assumes the computer is secure when actual security has vanished.

Another side of this is a phenomenon called security theatre where ineffective security measures such as screening of airline passengers based on static databases are introduced with little real increase in security or even, according to the critics of one such measure - Computer Assisted Passenger Prescreening System - with an actual decrease in real security.

Sometimes if it is perceived that there is security then there will be an increase in actual security, even if the perception of security is mistaken.

Sometimes a sign may warn that video surveillance is covering an area, and even if there is no actual visual surveillance then some malicious agents will be deterred by the belief that there may be.

Often when there is actual security present in an area, such as video surveillance, an alarm system in a home, or an anti-theft system in a car such as a LoJack, signs advertising this security will increase its effectiveness, protecting the value of the secured vehicle or area itself.

Since some intruders will decide not to attempt to break into such areas or vehicles, there can actually be less damage to windows in addition to protection of valuable objects inside.

Without such advertisement, a car-thief might, for example, approach a car, break the window, and then flee in response to an alarm being triggered.

It is important for signs advertising security not to give clues as to how to subvert that security, for example in the case where a home burglar might be more likely to break into a certain home if he or she is able to learn beforehand which company makes its security system.

There is an immense literature on the analysis and categorisation of security.

In most security systems, the "weakest link in the chain" is the most important.

The situation is asymmetric since the defender must cover all points of attack while the attacker need only identify a single weak point upon which to concentrate.

Aviation Security is a combination of measures and material and human resources intended to counter the unlawful interference with the aviation security.

In the corporate world, various aspects of security were historically addressed separately - notably by distinct and often noncommunicating departments for IT security, physical security, and fraud prevention.

Today there is a greater recognition of the interconnected nature of security requirements, an approach variously known as holistic security, "all hazards" management, and other terms.
 
Inciting factors in the convergence of security disciplines include the development of digital video surveillance technologies and the digitization and networking of physical control systems.

SECURITY GUARD

A security guard or security officer is usually a privately and formally employed person who is paid to protect property, assets, and/or people.

Often, security officers are uniformed and act to protect property by maintaining a high visibility presence to deter illegal and/or inappropriate actions, observing, either directly, through patrols, or by watching alarm systems or video cameras for signs of crime, fire or disorder; then taking action and/or reporting any incidents to their client, employer and emergency services as appropriate.

Since at least the Middle Ages in Europe, the term watchman was more commonly applied to this function.

Many security firms and proprietary security departments practice the "detect, deter, observe and report" methodology.

Security officers are not required to make arrests but have the authority to make a citizen's arrest or otherwise act as an agent of law enforcement at the request of a police officer, sheriff, and others.

In addition to the methodology mentioned above, a private security officer's primary duty is the prevention and deterrence of crime.

Security personnel enforce company rules and can act to protect lives and property. In fact, they frequently have a contractual obligation to provide these actions.

Security officers are often trained to perform arrest and control procedures (including handcuffing and restraints), operate emergency equipment, perform first aid, CPR, take accurate notes, write detailed reports, and perform other tasks as required by the contractee they are serving.

Many security officers are required to go through additional training mandated by the state for the carrying of weapons such as batons, firearms, and pepper spray.

Some security officers are required to complete police certification for special duties.

In recent years, due to elevated threats of terrorism, most security officers are required to have bomb-threat training and/or emergency crisis training, especially those located in soft target areas such as shopping malls, schools, and any other area where the general public congregate.

One major economic justification for security personnel is that insurance companies, particularly fire insurance carriers will give substantial rate discounts to sites which have a 24-hour presence; for a high risk or high value venue, the discount can often exceed the money being spent on its security program.

Having security on site increases the odds that any fire will be noticed and reported to the local fire department before a total loss occurs.

the presence of security personnel tends to diminish "shrinkage," theft, employee misconduct and safety rule violations, property damage, or even sabotage.

Many casinos hire security guards to protect money when transferring it from the casino to the casino's bank.

Security personnel may also perform access control at building entrances and vehicle gates; meaning, they ensure that employees and visitors display proper passes or identification before entering the facility.

Security officers are often called upon to respond to minor emergencies such as lost persons, lockouts, dead vehicle batteries, and to assist in serious emergencies by guiding emergency responders to the scene of the incident, helping to redirect foot traffic to safe locations, and by documenting what happened on an incident report.

Armed security officers are frequently contracted to respond as law enforcement until a given situation at a client location is under control and/or public authorities arrive on the scene.

Patrolling is usually a large part of a security officer's duties.

Often these patrols are logged by use of a guard tour patrol system, which require regular patrols.

The most commonly used form used to be mechanical clock systems that required a key for manual punching of a number to a strip of paper inside with the time pre-printed on it.

Regular patrols are, however, becoming less accepted as an industry standard, as it provides predictability for the would-be criminal, as well as monotony for the security officer on duty.

Random patrols are easily programmed into these systems, allowing greater freedom of movement and unpredictability. Global positioning systems are also easing their way into the market as a more effective means of tracking officer movement and patrol behavior.


Although security officers differ greatly from police officers, military personnel, federal agents/officers, and the like, the United States has a growing proportion of security personnel that have former police or military experience, including senior management personnel.

Some security officers, young people in particular, use the job as practical experience to use in applying to law enforcement agencies.

Industry terms for various security personnel include: Security guards, security agents, watchmen, security officers, safety patrol, Armed Security, Private Police, Company police, Loss Prevention, Bodyguards, Executive Protection Agents, or Access Managers.

Other job titles in the security industry include dispatcher, receptionist, driver, supervisor, alarm responder, mall security officer, private patrol officer, Private Patrol Operator, and manager.

In Canada, private security falls under the jurisdiction of Canada's ten provinces and three territories.

All ten of Canada's provinces and one of its territories, the Yukon have legislation that regulates the contract security industry.

These eleven jurisdictions require that companies that provide security guard services and their employees be licensed.

Most provinces in Canada regulate the use of handcuffs and weapons by contract security companies and their employees, either banning such use completely or permitting it only under certain circumstances.

Canada's federal laws also restrict the ability of security guards to be armed.

Security personnel are not police officers, unless they are security police, but are often identified as such due to similar uniforms and behaviors, especially on private property.

Security personnel in the U.S. derive their powers not from the state, as public police officers do, but from a contractual arrangement that give them 'Agent of the Owner' powers.

Some jurisdictions do commission or deputize security officers and give them limited additional powers, particularly when employed in protecting public property such as mass transit stations.

Additionally, security officers may also be called upon to act as an agent of law enforcement if a police officer, sheriff's deputy, etc. is in immediate need of help and has no available backup.

Some security officers do reserve police powers and are typically employed directly by governmental agencies.

Other local and state governments occasionally enter into special contracts with security agencies to provide patrol services in public areas.

The vigiles were soldiers assigned to guard the city of Rome, often credited as the origin of both security personnel and police, although their principal duty was as a fire brigade.

There have been night watchmen since at least the Middle Ages in Europe; walled cities of ancient times also had watchmen.

A special chair appeared in Europe sometime in the late Middle Ages, called the watchman's chair; this unupolstered wooden chair had a forward slanting seat to prevent the watchman from dozing off during his watch.

In 1980, musician John Lennon was fatally shot in front of his own apartment house, The Dakota, by a former security guard, Mark David Chapman. 

Christoph Meili, night guard at a Swiss bank, became a whistle blower in 1997. He told about the bank destroying records related to funds of Holocaust victims, whose money the bank was supposed to return to their heirs.

Derrick Brun, an unarmed security guard employed by the Red Lake School District in Minnesota, was praised by President Bush for his heroic role in protecting children during the 2005 Red Lake High School Massacre: "Derrick's bravery cost him his life, and some Americans honor him".