The definition given in a UN study, in 1986, is interesting as a contribution to the understanding of the concept of security, “Security is a state at which countries think that there is no danger of military attack, political pressure, or economic coercion, so that they can develop and progress freely.

    * With respect to classified matter, the condition that prevents unauthorized persons from having access to official information that is safeguarded in the interests of national security.
    * Measures taken by a military unit, an activity or installation to protect itself against all acts designed to, or which may, impair its effectiveness.

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 people attempting to cause destruction.