# Protozoa --- **Protozoa** are an (informal?) kingdom in the domain [[eukaryote|eukarya]] that are not animals, plants, or fungi. While exceptions exist, they are primarily [[microbe|unicellular]]. ## History At one time, simple organisms such as amoebas and single-celled algae were classified together in a single taxonomic category: the kingdom Protista. However, the emergence of better genetic information has since led to a clearer understanding of [[evolution|evolutionary]] relationships among different groups of protists, and this classification system was rendered defunct. Understanding protists and their evolutionary history continues to be a matter of scientific discovery and discussion. ___