Power is usually defined as the ability to impose one's will on others, or to pursue one's interests on the expense of others'. Violence or other kinds of force, or the threat of such force, can be used to exercise power (coercion).
Political analysis often personifies nation states as powers, discussing superpowers, great powers, second-order powers and "European powers", for example, with convenient simplicity as manifestations of Realpolitik. In Western thought these terms are generally qualitative terms. In current Chinese political thinking national power can be measured quantitatively using an index known as comprehensive national power. Chinese political thought also distinguishes between various forms of national power. In particular, hard power (military power) stands in contradistinction to soft power (economic or cultural or persuasive power).
States have always had variable levels of powers and a number of terms have been developed to describe this continuum.