How do gains from trade arise?

Gains from trade arise when countries or individuals specialize in producing goods and services in which they have a comparative advantage, meaning they can produce them more efficiently than others. By trading, they can obtain other goods at a lower opportunity cost than if they produced them independently. This specialization and exchange lead to an overall increase in total production and consumption, benefiting all parties involved. Ultimately, trade allows for a more efficient allocation of resources, enhancing economic welfare.