Fungi are beneficial to humans as sources of food and as essential support for other types of food. They create important medicines and are even used as biological insecticides. They are also vital decomposers, or saprotrophs, that break down organic waste into more useful forms.
Between 80 percent and 90 percent of trees and grasses cannot survive without a symbiotic relationship with fungi in the soil. This makes the fungi essential for growing a large majority of food crops, even when they are not consumed directly.
Fungi can also protect food crops by acting as pathogens to pest insects. The fungi species that do this have evolved to only attack certain insect species and leave plants unharmed. They grow through the insects' bodies and eventually emerge to spread their spores to other bugs.
Fungi are also important for food processing and are essential ingredients in certain types of cheese and in bread making and alcohol fermentation. The blue coloring in blue cheese is a type of fungus.
Fungi are also a major source of antibiotics, immunosuppressants, steroid precursors and substances that stop bleeding. Fungi are useful to research because they grow easily, like bacteria, but are much closer in cell structure and genetics to humans.