These questions have been central in economic science since the appearance of modern economics with Adam Smith in the second half of the 18th century. During the last 20-30 years much has happened within the area, so today one can talk about a traditional theory and a newer theory building, although quite differentiated.
The newer theories look at differentiated products, large-scale production and specialization of business activity, technology and incomplete competition. They also include economic growth and capital movements. When trade and capital movements occur at the same time, cumulative processes often start creating greater economic inequality. The object of this presentation is to use an understandable language without application of technical specialities.