The ultimate source of profit, the driving force behind capitalist production, is the unpaid labor of workers. Exploitation forms the foundation of the capitalist system.
All the billions in bonuses for the Wall Street bankers, every dividend paid to the shareholders of industrial corporations, every dollar collected by capitalist landlords, all of this is the result of the uncompensated labor of working class people.
And because exploitation is at the root of capitalism, it follows that the only way to do away with exploitation is to achieve an entirely different Society.
Exploitation is not unique to capitalism. It has been a feature of all class societies, which are divided into two main classes, an exploited class that produces the wealth and an exploiter class that expropriates it.
Under slavery, exploitation is naked and obvious to exploiter and exploited alike. The slave is forced by sword and lash to work for the master, who provides just enough to keep the slave alive. All the rest of the fruits of their labor are forcefully appropriated by the slaveowner.
Under feudalism, the serfs work on a plot of land that belongs to the lord. They work for part of the time for themselves, producing their means of subsistence, and the rest of the time, the product belongs to the lord.
The terms of exploitation are clear to serf and lord alike. The serf labors for the lord, and receives nothing from the lord in return.
Under Capitalism, the exploitative nature of labor is hidden by the wage system. Except in cases of outright fraud, workers are hired, labor for a given amount of time and receive a wage in return.
It appears on the surface that an equal exchange has taken place, but this is not the case. The distinction between labor-power and labor is the key to understanding exploitation under capitalism.
When a capitalist pays a worker a wage, they are not paying for the value of a certain amount of completed labor, but for labor-power. The soaring inequality in contemporary society illustrates this.
An increasing proportion of the wealth produced by workers swelled the pockets of the superrich, who did not compensate the workers for their increased production on the job.
Exploitation forms the basis of all the profits shared among the entire capitalist class.
It is not simply the case that the wealthy have a lot while workers have little; capitalists accumulate wealth through a system of organized theft from the working class.