Economics and choices exist because of scarcity, where all natural resources are limited. Therefore, we must make specific choices so that we can use our resources to the best of our abilities.
For example, Brazil is the world's largest coffee producer, and America is capable of producing tons of oil. These two could easily trade with each other as one specializes in producing different goods. It could be argued that America could produce their own coffee, or Brazil their own oil, but if one country produces more of that particular good than the other then they will reap more benefits trading than producing it themselves.
