The role of a food web is to illustrate the complex feeding relationships among organisms in an ecosystem. A food web showcases how energy and nutrients flow through various trophic levels, including producers, consumers, and decomposers. This interconnected network highlights the dependency of species on one another for survival, demonstrating the impact that the removal or addition of a species can have on the entire ecosystem. By understanding food webs, ecologists can assess ecological health and predict the consequences of environmental changes.