US government has a limited power because it cannot do certain things, and specifically it is not allowed to breach certain individual freedoms: so it can be said that the motivation for a limited government is to protect individual freedoms.
See for example the text of the first amendment:
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof" - this limits the power of the government so that people have a freedom to practice their religion.
Trade is when two or more people exchange items such as food , money , books and etc...
When our country = America ( USA ) trades goods such as money , or food and medical supplies to other countries ( Nations ) to help them and in return we might get more supporters or better Technology.
I really hope that this helps you out a lot.
eventually, the supplies for that stuff would run out and the product being produced would go "extinct"
