Nations are defined as distinct political entities characterized by a defined territory, a permanent population, a government, and the capacity to enter into relations with other nations. They often share common cultural, historical, and social traits, which contribute to their identity. Examples of nations include France, Japan, and Brazil, each with unique traditions and governance structures. The concept of nations is crucial in international relations, as they interact through diplomacy, trade, and treaties. Organizations like the United Nations facilitate cooperation among nations to address global challenges such as climate change, security, and human rights, promoting peace and development worldwide.