Final answer:
An independent country with the ability to make decisions on internal and external matters is a sovereign state, maintaining full control over governance, resources, and international relations following international recognition and often UN membership.
Step-by-step explanation:
A country that is independent in taking decisions on internal and external matters possesses sovereignty. Sovereignty refers to the ultimate authority over a territory, granting the state the absolute right to govern itself, make war or peace, and enter into treaties or alliances with other nations.
This autonomy means that it operates independently of any foreign power, managing its resources, and partaking in international relations as it sees fit. Reflecting on history, the post-World War II era marked significant strides in decolonization, where an overwhelming number of territories gained independence and consequently multiplied the member states of the United Nations. Through the rejection of colonial rule and the drive for self-determination, these states acquired the characteristics akin to European sovereign nations, with defined borders, governments, and national symbols. However, sovereignty goes beyond mere symbolisms; it is the capacity for a state to act to protect its interests and maintain its existence in the international system.