This video is part of Crash Course World History, written by Raoul Meyer and Teva Vidal, and presented by John Green.
Capitalism arose as higher agricultural productivity began to give people leisure and spare money to spend on what we now call consumer goods. Its rise was not harmonious, as the 17th-20th-century Enclosure Acts put hitherto public land into private hands, facilitating the construction of industrial premises.
In 19th-century Britain the miserable conditions of factory workers triggered the formation of unions, and socialism emerged in response to the threat that industrial capitalism (driven not by human need, but by the desire for profit) posed to the working population.
Theorists such as the Utopian Charles Fourier, who was against violence, and others who wanted violent revolution, became influential. Then the ideas of historian Karl Marx seeded communist political systems, an extreme expression of socialism. These failed, and industrial capitalism dominates the global economy; the application of socialism now is arguably in how far we should go in regulating free markets.