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 is said to have two dialogues. Negative dialogue is about danger, risk, threat etc. Positive dialogue is about opportunities, interests, profits etc. Negative dialogue needs military equipment, armies, or police. Positive dialogue needs social capital, education, or social interaction.