Centipedes normally have a drab coloration combining shades of brown and red. Cavernicolous and subterranean species may lack pigmentation and many tropical Scolopendromorphs have bright aposematic colors. Size can range from a few millimeters in the smaller Lithobiomorphs and Geophilomorphs to about 30 cm in the largest Scolopendromorphs. Centipedes can be found in a wide variety of environments.

Worldwide there are estimated to be 8,000 species. Currently there are about 3,000 described species. Geographically, centipedes have a wide range, which reaches beyond the Arctic Circle. Centipedes are found in an array of terrestrial habitats from tropical rainforests to deserts. Within these habitats centipedes require a moist micro-habitat because they lack the waxy cuticle of insects and arachnids, and so lose water rapidly through the skin. Accordingly, they are found in soil and leaf litter, under stones and deadwood, and inside logs. In addition, centipedes are one of the largest terrestrial invertebrate predators and often they contribute a significant proportion to invertebrate predatory biomass in terrestrial ecosystems.