International mostly means something (a company, language, or organization) involving more than a single country. The term international as a word means involvement of, interaction between or encompassing more than one nation, or generally beyond national boundaries. For example, international law, which is applied by more than one country and usually everywhere on Earth, and international language which is a language spoken by residents of more than one country.
International Relations (IR) or International Affairs (IA) - commonly also referred to as International Studies (IS) or Global Studies (GS) - is the study of interconnectedness of politics, economics and law on a global level. Depending on the academic institution, it is either a field of political science, an interdisciplinary academic field similar to global studies, or an entirely independent academic discipline in which students take a variety of internationally focused courses in social science and humanities disciplines. In all cases, the field studies relationships between political entities (polities) such as sovereign states, inter-governmental organizations (IGOs), international non-governmental organizations (INGOs), other non-governmental organizations (NGOs), and multinational corporations (MNCs), and the wider world-systems produced by this interaction. International relations is an academic and a public policy field, and so can be positive and normative, because it analyses and formulates the foreign policy of a given state.
In brief, for the United States, Eurasian geostrategy involves the purposeful management of geostrategically dynamic states and the careful handling of geopolitically catalytic states, in keeping with the twin interests of America in the short-term: preservation of its unique global power and in the long-run transformation of it into increasingly institutionalized global cooperation. To put it in a terminology that hearkens back to the more brutal age of ancient empires, the three grand imperatives of imperial geostrategy are to prevent collusion and maintain security dependence among the vassals, to keep tributaries pliant and protected, and to keep the barbarians from coming together.
Zbigniew Brzezinski,The Grand Chessboard (1997).
The struggle for power is universal in time and space and is an undeniable fact of experience. It cannot be denied that throughout historic time, regardless of social, economic and political conditions, states have met each other in contests for power. Even though anthropologists have shown that certain primitive peoples seem to be free from the desire for power, nobody has yet shown how their state of mind can be re-created on a worldwide scale so as to eliminate the struggle for power from the international scene. … International politics, like all politics, is a struggle for power. Whatever the ultimate aims of international politics, power is always the immediate aim.
Hans Morgenthau, Politics Among Nations (1948).