[2] Until the late twentieth century the Zygentoma were regarded as a suborder of the Thysanura,[3] until it was recognized that the order Thysanura was paraphyletic, thus raising the two suborders to the status of independent monophyletic orders, with Archaeognatha as sister group to the Dicondylia, including the Zygentoma.

Silverfish are so-called because of the silvery glitter of the scales covering the bodies of the most conspicuous species (family Lepismatidae).

These three generally subequal, except in some members of the family Nicoletiidae, in which they are short, and the cerci are hard to detect.

[14] Silverfish may be found in moist, humid environments or dry conditions, both as free-living organisms or nest-associates.

[15] In domestic settings, they feed on cereals, paste, paper, starch in clothes, rayon fabrics and dried meats.

[17] Silverfish can sometimes be found in bathtubs or sinks at night, because they have difficulty moving on smooth surfaces and so become trapped if they fall in.

Wild species often are found in dark, moist habitats such as caves or under rocks, and some, particularly the Atelurinae, are commensals living in association with ant and termite nests, e.g., Trichatelura manni[18] and Allotrichotriura saevissima,[15] which lives inside nests of fire ants in Brazil.

In the past, a contact pheromone was assumed to be responsible for the aggregation and arrestment behaviour observed in Zygentoma.

The Nicoletiidae tend to be smaller, pale in colour, and often live in soil litter, humus, under stones, in caves (with reduced eyes) or as inquilines in ant or termite colonies.

[28] Some molecular phylogenies have found Tricholepidiidae to form an independent, more basal branch of insects unrelated to other zygentomans.

[29] The fossil record for Zygentoma is poor, though they must have diverged from all other insects either during the Carboniferous, or the Devonian if Leverhulmia is an example of the group.

The oldest fossils of the order are indeterminate specimens of Lepismatidae from the Santana Formation of Brazil, dating to the Aptian stage of the Early Cretaceous around 113 million years ago, with other specimens of Lepismatidae known from the Burmese amber of Myanmar, dating to around 100 million years ago.