International relations refers to the collective interactions of the international community, which includes individual nations and states, inter-governmental organizations such as the United Nations, non-governmental organizations like Doctors Without Borders, multinational corporations, and so forth. The term is also used to refer to a branch of political science which focuses on the study of these interactions. As an academic discipline, international relations encompasses a wide range of academic fields, ranging from history to environmental studies, and there are a number of areas of specific specialty, for academics who are interested in them.
The concept of international relations on some level is probably quite old, given that humans have been establishing governments and communicating with each other for thousands of years. However, many people agree that international relations truly began to emerge around the 15th century, when people started exploring the world and interacting with other governments and cultures. Organizations like the Dutch East India company were among the first multinational corporations, for example, while representatives of various European governments met with foreign governments to establish trade agreements and to discuss issues of mutual concern.
As one might imagine, international relations can get incredibly complex. It is also sometimes known as “foreign relations,” and specialists in this field do things like staffing diplomatic agencies abroad, providing consultation to businesses which are considering establishing branches overseas, and assisting charitable non-governmental organizations with their missions.