Karl Marx's works were written during the latter half of the nineteenth century, almost a century after the dawn of the industrial revolution. By this time, feudal relations of production had been replaced by capitalist relations throughout the developed world. Essentially, the shift was one from small-scale, independent production of goods to mass production. This was all made possible by the invention of engines and machines which soon replaced individuals as producers (because they allowed for commodities of a consistent quality to be manufactured using only a fraction of the labor as before - hence, cheaper). The industrial revolution changed life on our earth more than any other development to date in mankind's onward historical march.
What Marx did was to spell out how capitalism as a system of production fails to satisfy human needs and hurts all who live under it - both workers and capitalists. Marx defined capitalists as those who own the means of production under capitalism, and profit from their operation, i.e., the bosses, the ruling class. Workers are those who work for the bosses, who own nothing but their labor power, and who consequently are forced to sell this labor in order to earn a means of survival. In Marx's view, it is not by any means a fair trade.
His notion is that capitalist production alienates workers from themselves. Marx's concept of alienation is multifaceted; in one sense, workers are alienated by factory production because it removes them from the end product of their labors, reducing them to not hing more than "mere appendages of flesh in machines of iron." They are also alienated because their most creative potential, the act of work, becomes nothing more than a commodity, and worse, one which ends up in the hands of someone else!
For the most important way in which workers are alienated by capitalist production is that through its motions, workers are deprived of something that otherwise would be rightfully theirs. In the process of selling their labor, Marx argues, workers get ripped off. Some of their labor's value is lost, since producers of goods can only make a profit by charging potential consumers more than what the goods cost to produce. It is by not compensating workers fully for the value of their labor that producers make money from manufacturing.
Many arguments have been devised by capitalists to refute Marx's observations concerning owners' profits and the injustice of their origins. Perhaps the most straightforward justification of profits flowing to the owners of capital has been that profits are fair renumerations for the multitude of things that owners of capital must bankroll, procure, and maintain in order for large-scale production to take place and workers to be gainfully employed. Obviously, a considerable scale of organization is required before modern day manufacturing can occur in an ordered fashion. However, Marx stresses that under capitalism, present day owners are enjoying the fruits of labor expended by countless previous generations. Is it fair, he asks, that the invention and labor of thousands of years be the exclusive privilege of the wealthy few?
Marx foresaw capitalism's eventual downfall because of the contradictions inherent in its basic structure. Of necessity to a capitalist system's well-being is an ever-increasing flow of wealth from the working classes to the owners of capital. Marx's logical conclusion was that eventually, something would have to give. Oppressed workers the world over, once no longer able to bear their impoverishment, would rise up and seize control of all means of production from the capitalists.
What Marx did not foresee was that during the century after his death, capitalism's global penetration would create a whole new set of exploitative conditions. The size of the world's working class has been greatly enlarged; now, it is much of the third world whose labors prop up the abundance of our western standards of living. No longer is there as great a danger of communist revolution shaking the industrialized world from within, for most remaining workers in the developed world live at least reasonably comfortably. The impoverished workers who toil under oppressive conditions so that international capitalism may profit now do so in faraway lands. Are they capable of rising up in revolution against a west armed to the teeth with high-tech, trillion dollar militaries, not to mention atom bombs?
This is not to say the relationships between workers and capitalists as described by Marx do not still exist in our industrialized societies today, only that the scope of workers' exploitation by capitalists has expanded in other, global directions under new circumstances. When their jobs are not eliminated entirely by relocation of factories to the third world, workers in America today are still squeezed first and hardest by bosses looking to maintain profit levels during times of financial hardship. Workers are still robbed of the value of their labor through woeful undercompensation for their work. If you want to understand worker-owner dynamics under our world's current global capitalist framework, nothing can substitute for an understanding of Marx.