Millipedes are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derived from this feature. Each double-legged segment is a result of two single segments fused together. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter and can roll into a tight ball. Although the name "millipede" derives from Latin for "thousand feet", no species was known to have 1,000 or more until the discovery in 2020 of Eumillipes persephone, which can have over 1,300 legs. There are approximately 12,000 named species classified into 16 orders and around 140 families, making Diplopoda the largest class of myriapods, an arthropod group which also includes centipedes and other multi-legged creatures.

सहस्रपाद आर्थोपोडा संघ का एक प्राणी है। इसका शरीर लंबा एवं खण्डयुक्त तथा काइटिन के बाह्य कंकाल से ढका होता है। सिर पर एक जोड़ी श्रृंगिकाएँ होती हैं। धड़ के प्रत्येक खण्ड में दो जोड़े संधियुक्त पैर होते हैं। इसमें श्वसन अंग वायुनलियाँ हैं।और बर्षा ऋतु के समय इनको झुंड में देखा जा सकता है।