Cartilage is a resilient and smooth type of connective tissue. It is a semi-transparent and non-porous type of tissue. It is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints as articular cartilage, and is a structural component of many body parts including the rib cage, the neck and the bronchial tubes, and the intervertebral discs. In other taxa, such as chondrichthyans, but also in cyclostomes, it may constitute a much greater proportion of the skeleton. It is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. The matrix of cartilage is made up of glycosaminoglycans, proteoglycans, collagen fibers and, sometimes, elastin. It usually grows quicker than bone.

उपास्थि मानव शरीर एवं अन्य प्राणियों में पाया जाने वाला लचीला संयोजी उत्तक है। यह हमारी मज्जा में स्थापित कॉन्ड्रोसाइट्स कोशिकाओं से बने होते हैं। कान की हड्डी, नाक की हड्डी, अस्थियों के जोड़ आदि उपास्थि के बने हैं।