Previously, taxonomists classified all organisms into five kingdoms. These five kingdoms were: Fungi, Plantae, Monera, Protista, and Animalia. However, with more research, they discovered that they should be looking at the relationships between organisms in a different way. Currently, taxonomists generally classify organisms into three different domains, domains being a broader categorization than kingdoms. The three domains are Archaea, Bacteria, and Eukarya with six kingdoms under the three domains. Domain Archaea includes the Archaebacteria Kingdom. The Domain Bacteria includes the Eubacteria Kingdom. And Domain Eukarya has four kingdoms- Fungi, Plantae, Animalia, and Protista. This classification groups organisms based on their ribosomal RNA structure (the building blocks of ribosomes).
This photo has an organism from the Kingdom Fungi. The kingdoms within Domain Eukarya, excluding protists, are mainly multicellular and are classified based on the way they obtain food. Fungi are decomposers, meaning that they break down the remnants of dead organisms and organic wastes. These organisms absorb nutrients from sources outside of their bodies.