What happens to output in a production process as more labor is added, according to the law of diminishing marginal returns?

The law of diminishing marginal returns states that as more units of a variable input, such as labor, are added to a fixed input, like machinery or land, the additional output (or marginal product) from each new unit of labor will eventually decline beyond a certain point. Initially, adding more labor typically leads to an increase in output, as the additional workers can make better use of the available resources. However, after a certain level of labor input, the incremental output produced by each additional worker starts to decrease.

This situation occurs because, with a fixed amount of other resources, each new worker has less of those resources to work with, leading to less efficient production. For instance, if more workers are packed into a factory with a limited number of machines, they may hinder each other’s productivity due to congestion or overlapping tasks. This is why output continues to increase, but at a decreasing rate after reaching this point of diminishing returns, rather than continuing to rise indefinitely or remaining constant.