Countries have comparative advantage in those goods for which the required factors of production are relatively abundant. This is because the prices of goods are ultimately determined by the prices of their inputs. Goods that require inputs that are locally abundant will be cheaper to produce than those goods that require inputs that are locally scarce.
For example, a country where capital and land are abundant but labor is scarce will have comparative advantage in goods that require lots of capital and land, but little labor - grains, for example. Since capital and land are abundant, their prices will be low. Those low prices will ensure that the price of the grain that they are used to produce will also be low - and thus attractive for both local consumption and export. Labor intensive goods on the other hand will be very expensive to produce since labor is scarce and its price is high. Therefore, the country is better off importing those goo
The Ricardian model of comparative advantage has trade ultimately motivated by differences in labour productivity using different technologies. Heckscher and Ohlin didn't require production technology to vary between countries, so (in the interests of simplicity) the H-O model has identical production technology everywhere. ...
The H-O model removed technology variations but introduced variable capital endowments, recreating endogenously the inter-country variation of labour productivity that Ricardo had imposed exogenously. With international variations in the capital endowment (i.e. infrastructure) and goods requiring different factor proportions, Ricardo's comparative advantage emerges as a profit-maximizing solution of capitalist's choices from within the model's equations. (The decision capital owners are faced with is between investments in differing production technologies: The H-O model assumes capital is privately held.)
Bertil Ohlin published the book which first explained the theory in 1933. Although he wrote the book alone, Heckscher was credited as co-developer of the model, because of his earlier work on the problem, and because many of the ideas in the final model came from Ohlin's doctoral thesis, supervised by Heckscher.
Interregional and International Trade itself was verbose, rather than being pared down to the mathematical, and appealed because of its new insights.
 The 2x2x2 model
The original H-O model assumed that the only difference between countries was the relative abundances of labour and capital. The original Heckscher-Ohlin model contained two countries, and had two commodities that could be produced. Since there are two (homogeneous) factors of production this model is sometimes called the "222 model".
The model has variable factor proportions between countries: Highly developed countries have a comparatively high ratio of capital to labour in relation to developing countries. This makes the developed country capital-abundant relative to the developing nation, and the developing nation