What type of organisms primarily make up the kingdom Fungi?

The kingdom Fungi is primarily composed of molds and yeasts, which are distinct groups of organisms within this kingdom. Fungi are characterized by their cell walls made of chitin, which sets them apart from plants, whose cell walls are made of cellulose. Molds are typically filamental organisms that grow in multicellular structures called hyphae, forming a mycelium. Yeasts are unicellular fungi that reproduce mainly through budding. Both molds and yeasts play essential roles in ecosystems, contributing to decomposition, nutrient cycling, and even human industry, such as in the production of bread and beer. Their unique cellular structures and biological processes are fundamental to the definition of the Fungi kingdom.