The invisible hand is a term used by Adam Smith to describe the unintended social benefits of individual self-interested actions. The phrase was employed by Smith with respect to income distribution (1759) and production (1776). The exact phrase is used just three times in Smith's writings, but has come to capture his notion that individuals' efforts to pursue their own interest may frequently benefit society more than if their actions were directly intending to benefit society. Smith may have come up with the two meanings of the phrase from Richard Cantillon who developed both economic applications in his model of the isolated estate - wikipedia 
Smith first introduced the concept in The Theory of Moral Sentiments, written in 1759, invoking it in reference to income distribution. In this work, however, the idea of the market is not discussed, and the word "capitalism" is never used. By the time he wrote The Wealth of Nations in 1776, Smith had studied the economic models of the French Physiocrats for many years, and in this work the invisible hand is more directly linked to production, to the employment of capital in support of domestic industry. The only use of "invisible hand" found in The Wealth of Nations is in Book IV, Chapter II, "Of Restraints upon the Importation from foreign Countries of such Goods as can be produced at Home."
The idea of trade and market exchange automatically channeling self-interest toward socially desirable ends is a central justification for the laissez-faire economic philosophy, which lies behind neoclassical economics. In this sense, the central disagreement between economic ideologies can be viewed as a disagreement about how powerful the "invisible hand" is. In alternative models, forces which were nascent during Smith's lifetime, such as large-scale industry, finance, and advertising, reduce its effectiveness.