A fungus is a eukaryotic organism that cannot produce its own food via photosynthesis, has cell walls that contain chitin and reproduces via the use of spores, according to the University of Hawaii. Common examples of fungi include mushrooms, molds and yeasts.
Fungi can be either unicellular or multicellular, according to the University of Hawaii. Since they cannot produce their own food, they frequently consume decaying organic matter instead. Many also live as parasites on other organisms.
While fungi were once considered to be a type of plant, scientists later realized that they are a separate kingdom of life. Fungi are actually more closely related to animals than they are to plants, according to ScienceDaily.com