Fungi are classified based on their methods of sexual reproduction. Each division of fungi has a unique method of reproduction, although all fungi reproduce sexually, and these characteristics account for their grouping into distinct classifications.
The exception to sexual reproduction in fungi is the family deuteromycota, a catch-all term for fungi that have gravitated away from sexual reproduction. At the start of the 21st century, there was considerable uncertainty as to how to classify these deuteromycota.
Chytridiomycota are chytrids, fungal parasites that grow keratin and chitin. They are a very ancient species of fungi that reproduce through the production of zoospores. These spores disseminate through the atmosphere to seed new fungus. Atypically, they use glyocen as a compound in which to store energy.
Zygomycota are bread molds, very common fungi which grow frequently on human food, especially bread. These molds often appear furry and in fact have many delicate fronds and tendrils. Ascomycota comprise yeasts and sac fungi which, while they reproduce sexually, often manifest that reproduction through bizarre methods such as budding or cellular binary fission.
Basidiomycota are the fourth general classification for fungi. This classification includes many large life forms and many examples of what are commonly referred to as mushrooms and toadstools. They are large, fleshy organisms that often boast gills and caps.