To understand comparative advantage, it is best to start with its simpler cousin: absolute advantage. The concept of absolute advantage simply says that if some foreign nation is a more efficient producer of some product than we are, then free trade will cause us to import that product from them, to the benefit of both nations. It benefits us because we get the product for less than it would have cost us to make it ourselves. It benefits the foreign nation because it gets a market for its goods. And it benefits the world economy as a whole because it causes production to come from the most efficient producer, maximizing world output.