Marxism
Most workers work for companies owned by either capitalists or "petit-bourgeois" (small-time exploiters). The capitalist pays the worker in exchange for the worker's time. The capitalist has bought a period of time from the worker, which the worker must then use to labor for the capitalist. According to Marxist thinking, this is the only way that a capitalist can create extra money from a commodity (a piece of merchandise).  The capitalist exploits the worker's time as much as they can. The capitalist receives a certain price for the commodity the worker made.  The capitalist builds up capital by paying the worker less than that price.  In this way, the capitalist exploits the worker's labor by: