Cockroaches, like all insects, are members of the animal kingdom and phylum Arthropoda. The approximately 4,600 species of cockroaches belong to the class Insecta and the order Blattodea.
Cockroaches are grouped into the order Blattodea, which is part of the superorder Dictyoptera, meaning "net-like wing." The wing structure of the cockroach family is a useful key to identifying their place in the taxonomic tree of insects. Dictyoptera are classed within Neoptera, which includes insects that can bend their wings over their abdomens. Above this level, the group is again classed by its wings in the subclass Pterygota, which refers to the vast majority of insects including some wingless species whose ancestors were winged.
As insects, cockroaches have six legs and an exoskeleton. They breathe through small openings in their flanks called spiracles. The phylum Arthropoda is enormous and contains most of the multicellular animals on Earth. In addition to insects such as cockroaches, arthropods include arachnids, crustaceans and long-extinct trilobites.
Above the level of the animal kingdom, a cockroach is a Eukaryota, which is one of the three major domains of life. Eukaryota refers to their cells having a discreet nucleus and a number of organelles. The other two major domains of life are Archaea and Eubacteria.