Comparative advantage is an economic principle that describes the ability of one entity (individual, firm, or country) to produce a particular good or service at a lower opportunity cost than others. Opportunity cost refers to the value of the next best alternative that must be forgone in order to produce something else. In the context of international trade, countries are said to have a comparative advantage if they can produce a good or service at a lower opportunity cost than other nations. This principle forms the basis for specialization and trade, where each participant focuses on producing what they can produce most efficiently, leading to mutual benefits and overall efficiency in the global economy.