Fungal species are a diverse group of organisms that belong to the kingdom Fungi. They play essential roles in ecosystems, including decomposing organic matter and forming symbiotic relationships with plants through structures called mycorrhizae. Fungi can be found in various environments, from soil to decaying wood, and they reproduce through spores. There are over 100,000 known fungal species, with many more yet to be discovered. Fungi can be classified into several categories, including mushrooms, yeasts, and molds. Some species are beneficial, used in food production and medicine, while others can cause diseases in plants, animals, and humans.