Quick Answer: Security is protection from, or resilience against, potential harm. Beneficiaries of security may be persons and social groups, objects and institutions, ecosystems, or any other entity or phenomenon vulnerable to unwanted change. Security mostly refers to protection from hostile forces, but it has a wide range of other senses: for example, as the absence of harm; as the presence of an essential good; as resilience against potential damage or harm; as secrecy; as containment; and as a state of mind. Security is both a feeling and a state of reality. One might feel secure when one is not actually so; or might feel insecure despite being safe. This distinction is usually not very clear to express in the English language. The term is also used to refer to acts and systems whose purpose may be to provide security. Security can be physical and virtual.