Why is security is 'contested concept'?

It has various meanings attributed to it, it is not plainly definable in a way that all agree with. Its meanings are not merely the consequence of different political commitments and beliefs of individuals, but also by broader cultural factors, as well as by the socio-economic and professional environments. We are dealing with a complex patterns of beliefs and perceptions.

Concepts of security have one thing in common - they're based on fear or actual and potential attacks on public authorities, persons and property. Globalisation has considerably widened the kinds of actions considered to threaten security, through technological and social change. While traditionally, security emphasised the absence of threats to one's immediate well-being, we now consider security as broader than this, absence of threats to economic prosperity, to our environment and to our vital energy supplies. Many people also disagree over what will actual constitute security - such as those who believe that joining collective institutions for security such as the UN or NATO, or realists that think security is achieved through a balance of power, where no one state can dominate the playing field of world politics. The traditional concept of security involved 'arming up', being militarily strong enough to protect the country from outside threats, but more recently, there is emphasis on cooperation and comprehensive collective measures, such as those on Nuclear Weapons - NPT, and those on terrorism - UN Resolutions.