In other words, wealth under capitalism is not produced by individuals working on their own, but is produced by the cooperative labor of many people. So, while the wealth is created by a majority in society, it is owned and controlled not by the majority, but by an elite within it. The introduction of socialized production was one of the progressive features of capitalism as was the introduction of the world market, which organizes production not just on a national scale but on a world scale. Today, when multinational corporations need to bring together raw materials, labor, transportation, and sales they have to bring together a crude world plan of production that involves all five continents. Both of these features of capitalism, socialized production and the possibility of a world plan of production are key ingredients for a socialist society.
Capitalism is a system based on production for profit.
There profits come from the unpaid labor of the working class, as workers are not paid for what they produce, but an agreed wage. For the system to work, and for the bosses to make a profit, the worker has to produce more than the value of his or her wages. For the bosses to realize the profit of the goods produced by the worker, they have to be sold at their real market value or thereabout. But the market for these goods is mainly provided by working people who are the great majority in society. The main market is for mass produced, cheap goods for the needs of the majority of people.