Proteoglycans are large molecules found in the extracellular matrix of tissues, composed of a core protein and one or more glycosaminoglycan (GAG) chains. They play a crucial role in providing structural support, regulating cell behavior, and maintaining the hydration of tissues. Commonly found in cartilage, they help to resist compressive forces and contribute to the overall resilience of the tissue. These molecules are essential for various biological processes, including cell signaling and tissue repair. In addition to cartilage, proteoglycans are present in other tissues such as skin and blood vessels, influencing their function and health.