A millipede is a long, segmented arthropod belonging to the class Diplopoda. They typically have two pairs of legs per body segment, which gives them their name, meaning "thousand feet." Millipedes are usually found in damp environments, such as leaf litter or soil, where they play a vital role in decomposing organic matter. Unlike centipedes, which are carnivorous, millipedes are primarily herbivorous, feeding on decaying plant material. They have a cylindrical body and can range in size from a few millimeters to over 30 centimeters. Millipedes are generally harmless to humans, although some species can secrete toxic substances as a defense mechanism.