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Safety 
is the state of being "safe" (from French sauf), the condition of being protected against physical, social, spiritual, financial, political, emotional, occupational, psychological, educational or other types or consequences of failure, damage, error, accidents, harm or any other event which could be considered non-desirable. Safety can also be defined to be the control of recognized hazards to achieve an acceptable level of risk. This can take the form of being protected from the event or from exposure to something that causes health or economical losses. It can include protection of people or of possessions.
Meaning

There are two slightly different meanings of safety. For example, home safety may indicate a building's ability to protect against external harm events (such as weather, home invasion, etc.), or may indicate that its internal installations (such as appliances, stairs, etc.) are safe (not dangerous or harmful) for its inhabitants.

Types of safety

It is important to distinguish between products that meet standards, that are safe, and those that merely feel safe. The highway safety community uses these terms:

Normative safety

Normative safety is a term used to describe products or designs that meet applicable design standards and protection.

Substantive safety

Substantive, or objective safety means that the real-world safety history is favorable, whether or not standards are met.

Perceived safety

Perceived, or subjective safety refers to the level of comfort of users. For example, traffic signals are perceived as safe, yet under some circumstances, they can increase traffic crashes at an intersection. Traffic roundabouts have a generally favorable safety record,^{[citation needed]} yet often make drivers nervous

System safety and reliability engineering

System safety and reliability engineering is an engineering discipline. Continuous changes in technology, environmental regulation and public safety concerns make the analysis of complex safety-critical systems more and more demanding.

A common fallacy, for example among electrical engineers regarding structure power systems, is that safety issues can be readily deduced. In fact, safety issues have been discovered one by one, over more than a century in the case mentioned, in the work of many thousands of practitioners, and cannot be deduced by a single individual over a few decades. A knowledge of the literature, the standards and custom in a field is a critical part of safety engineering. A combination of theory and track record of practices is involved, and track record indicates some of the areas of theory that are relevant. (In the USA, persons with a state license in Professional Engineering in Electrical Engineering are expected to be competent in this regard, the foregoing notwithstanding, but most electrical engineers have no need of the license for their work.)

Safety is often seen as one of a group of related disciplines: quality, reliability, availability, maintainability and safety. (Availability is sometimes not mentioned, on the principle that it is a simple function of reliability and maintainability.) These issues tend to determine the value of any work, and deficits in any of these areas are considered to result in a cost, beyond the cost of addressing the area in the first place; good management is then expected to minimize total cost.

Safety measures

Safety measures are activities and precautions taken to improve safety, i.e. reduce risk related to human health. Common safety measures include:

• Root cause analysis to identify causes of a system failure and correct deficiencies.
• Visual examination for dangerous situations such as emergency exits blocked because they are being used as storage areas.
• Visual examination for flaws such as cracks, peeling, loose connections.
• Chemical analysis
• X-ray analysis to see inside a sealed object such as a weld, a cement wall or an airplane outer skin.
• Destructive testing of samples
• Stress testing subjects a person or product to stresses in excess of those the person or product is designed to handle, to determining the "breaking point".
• Safety margins/Safety factors. For instance, a product rated to never be required to handle more than 200 pounds might be designed to fail under at least 400 pounds, a safety factor of two. Higher numbers are used in more sensitive applications such as medical or transit safety.
• Implementation of standard protocols and procedures so that activities are conducted in a known way.
• Training of employees, vendors, product users
• Instruction manuals explaining how to use a product or perform an activity
• Instructional videos demonstrating proper use of products
• Examination of activities by specialists to minimize physical stress or increase productivity
• Government regulation so suppliers know what standards their product is expected to meet.
• Industry regulation so suppliers know what level of quality is expected. Industry regulation is often imposed to avoid potential government regulation.
• Self-imposed regulation of various types.
• Statements of Ethics by industry organizations or an individual company so its employees know what is expected of them.
• Drug testing of employees, etc.
• Physical examinations to determine whether a person has a physical condition that would create a problem.
• Periodic evaluations of employees, departments, etc.
• Geological surveys to determine whether land or water sources are polluted, how firm the ground is at a potential building site, etc.