Homoptera is a deprecated suborder of order Hemiptera; recent morphological studies and DNA analysis strongly suggests that the order is paraphyletic. It was therefore split into the suborders Sternorrhyncha, Auchenorrhyncha, and Coleorrhyncha.
However, there is currently debate over the monophyly of Auchenorrhyncha. See Heteroptera and Prosorrhyncha for more information on such points.
The Homoptera as recognized over the last century or so, include the aphids, scale insects, cicadas, and leafhoppers. They are all "true bugs" and they all have sucking mouthparts.