Taxonomy is the discipline of defining groups of organisms. The classic Linaean taxonomy is divided into Kingdom, Phylum, Class, Order, Family, Genus, Species. Over time this system has evolved to include 6 kingdoms: Archaea, Eubacteria, Animal, Plant, Fungi, Protist. The last four of these all fall into the domain of Eukaryotes.
The 6 Kingdoms - read this pdf file to learn about the 6 kingdoms and the major subdivisions of each. Know the basic characteristics of each kingdom and know and appreciate what various creatures in each kingdom do for the planet and for humans.