The Thysanura are a group of small wingless insects. While most species spend their time in decaying material, leaf litter and the like, a number of them have found urban living preferrable. Silverfish are commonly found in older buildings and any place they can live undisturbed on old newspapers and books. Firebrats, however, get their name from their preference for warm places, such as near ovens and heaters.
For more information on the phylogeny and diversity of the Thysanura, try the Thysanura page at the Tree of Life. Or learn interesting facts about Thysanura at the UD College of Agricultural Sciences Insect Database and at the Wonderful World of Insects.