Production theory: the first meaning is to compare material production with spiritual production, not specifically referring to products in a certain historical period; The second meaning refers to the actual creative process; The third meaning means that in the period of capital development, all production is to create value for capital, and everything has the property of commodity.

Utility theory is an economic theory that explains the value and its formation process by the ability of goods to satisfy people's desires or people's subjective psychological evaluation of the utility of goods.

Cost theory: every country has its absolutely favorable production conditions suitable for producing a certain product. It is beneficial for all exchange countries to specialize in production and then exchange with each other. This is the absolute cost theory.

These things cover a large area. I suggest reading The Wealth of Nations and Das Kapital, which will be introduced in detail!