Karl Marx's concept of class is central to his entire theoretical framework, particularly his analysis of capitalism and his theory of historical materialism. Unlike conventional understandings of class based on income, status, or occupation, Marx defined class primarily by one's relationship to the means of production.

At its core, Marx identified two primary antagonistic classes in capitalist society:

1. The Bourgeoisie: This class comprises the owners of the means of production – the factories, land, capital, and technology necessary to produce goods and services. They derive their wealth and power from owning these productive assets and employing others to work them. The bourgeoisie's primary interest is to maximize profit.

2. The Proletariat: This class consists of the wage laborers who do not own the means of production. To survive, they must sell their labor power to the bourgeoisie. They are the producers of wealth but do not own the products of their labor. The proletariat's primary interest is to improve their working conditions, wages, and ultimately, to end their exploitation.

Marx argued that the relationship between these two classes is inherently one of exploitation. In the capitalist system, workers produce more value than they receive in wages. This 'surplus value' is appropriated by the bourgeoisie as profit. This exploitation is not a moral failing of individual capitalists but an inherent feature of the capitalist mode of production itself.

For Marx, history is essentially a history of class struggle. He believed that throughout history, different societies have been characterized by different modes of production, each giving rise to distinct class structures and inherent conflicts. In capitalism, the struggle between the bourgeoisie and the proletariat is the driving force of social change.

Initially, the proletariat may suffer from false consciousness, meaning they do not fully recognize their exploited position or their shared interests as a class. They might be swayed by dominant ideologies (religion, nationalism, consumerism) that obscure the true nature of their oppression. However, as capitalism develops, leading to increased exploitation, alienation, and concentration of wealth, workers begin to develop class consciousness. This is the realization of their common plight, their collective power, and the need for unified action against the bourgeoisie.

This growing class consciousness, coupled with the inherent contradictions of capitalism, would eventually lead to a proletarian revolution. Marx envisioned this revolution as the overthrow of the capitalist system and the seizure of state power by the working class. This would be followed by a transitional phase, the dictatorship of the proletariat, where the state would be used to dismantle capitalist structures and suppress counter-revolutionary forces.

Ultimately, Marx's vision was the establishment of a classless society, or communism. In this final stage, private ownership of the means of production would be abolished, leading to collective ownership. With the elimination of private property and the division of labor, class distinctions would disappear, and the state, as an instrument of class oppression, would wither away. This would usher in an era of true human emancipation, where individuals could realize their full potential in a society of abundance and freedom.

In summary, Marx's concept of class is a dynamic, relational, and conflict-driven understanding that views class as the fundamental determinant of social structure and the primary engine of historical change, ultimately leading to a revolutionary transformation towards a communist society.