You may hear the term 'International Relation' from News. Which means you are familiar with the term. International relation is a discipline in which students study the relation between two states or countries. For the first time, Jeromy Bentham used the term International for the law of Nations in the 18th century. Later on the term International relation was used to define relations between sovereign states.
The relation between two states is a complicated matter and it involves other Non-state actors. The Non-state actors influence the relation between two states. IR is not just limited to just politics between states but it also includes social structures such as culture, economic and domestic politics.
It is difficult to define IR in a few words because it is a vast field and overlaps several other fields. The primary focus of IR is the interaction between states. It is also concerned with Non-state actors, international security, globalization, terrorism, International environment as well as military conflicts and studies, etc. If we look at issues like these it goes beyond the sphere of relations between states. And then there are Non-state actors which make it more complicated. To make it easy and helpful for primary understanding we oversimplified it. In the early time, the main focus of IR was to study the interaction between sovereign states. But its scope has become vast today.