This infraclass is often referred to as the wing-folding insects. The evolution of sclerites in the wing base, which permits each wing to twist around the third of three axillary sclerites and place the wings over the abdomen and in this manner out of the way when at rest, was an apomorphic feature. Exceptions exist for the secondarily specialized forms. Venation of the wings is with few or no triadic veins and usually with a less dense reticulation of cross-veins then the Paleoptera. The primitive Neopteran insect had mandibulate mouthparts, palpi with five maxillary and three labial segments, simple multiarticulate antennae, large compound eyes and three ocelli, and five-segmented tarsi, but some descendant taxa have departed widely from these conditions. Metamorphosis is slight to complete.
The Neoptera is an assemblage of polyphyletic groups which deserves more study. Probably the most cautious but correct placing of the taxa was proposed by Kristensen (1991). The Endopterygota and the Hemipteroid assemblage are sister groups, placed together in the polyphyletic assemblage of other taxa belonging to the Neoptera (see Neoptera).