Fungi are eukaryotic (you-carry-ah-tick) organisms—their DNA is enclosed in a nucleus. Many of them may look plant-like, but fungi do not make their own food from sunlight like plants do.
Some fungi are quite useful to us. We've tapped several kinds to make antibiotics to fight bacterial infections. These antibiotics are based on natural compounds the fungi produce to compete against bacteria for nutrients and space. We use Saccharomyces cerevisiae (sack-air-oh-my-seas sair-uh-vis-ee-ay), aka baker's yeast, to make bread rise and to brew beer. Fungi break down dead plants and animals and keep the world tidier. We're exploring ways to use natural fungal enemies of insect pests to get rid of these bugs.
There are some nasty fungi that cause diseases in plants, animals and people. One of the most famous is Phytophthora infestans (fie-tof-thor-uh in-fes-tuhns), which caused the Great Potato Famine in Ireland in the mid-1800s that resulted in a million deaths. See the news story on Phytophthora in the News section. Fungi ruin about a quarter to half of harvested fruits and vegetables annually.
Many more interesting facts about fungi can be found throughout the Microbe website, so keep clicking and reading.
You can also get a lot of details about fungi and see some cool images at The Microbial World website.