The Fungi

Fungi, singular, fungus, is a group of eukaryotic, non-phototrophic organisms with rigid cell walls, that includes mushrooms, molds and yeasts. This definition has some words in it that probably need definitions of their own. Eukaryotic simply means that fungal cells have a nucleus, like plant and animal cells, which distinguishes them from the Bacteria and Archaea. Non-phototrophic means that they can't use light for energy because they lack chlorophyll, distinguishing them from plants.