The systematics of nematodes is reviewed, including: an overview of the general biology, ecology, scientific and economic
importance of the group; a history of classification; evolutionary affinities and origins of nematodes; and the current
diagnosis of the group. Alternative classifications within the Phylum Nematoda are discussed, and a classification to
family level incorporating the latest molecular, developmental and morphological research is presented. This classification
reflects the current views on evolution within the phylum, as well as significant areas of uncertainty, particularly
related to the early evolution of nematodes. It includes 5 classes, 9 subclasses, 23 superorders, 39 orders, 52 suborders,
89 superfamilies and 241 families. There are few changes at the superfamily and family levels.