Aggrecan is a large proteoglycan found primarily in cartilage, which is the flexible tissue that cushions joints. It plays a crucial role in providing cartilage with its unique ability to withstand compressive forces, helping to maintain the structure and function of joints. Aggrecan is composed of a core protein with numerous glycosaminoglycan (GAG) chains attached, which attract water and contribute to the gel-like properties of cartilage. In addition to its structural role, aggrecan is involved in signaling pathways that regulate cell behavior and tissue maintenance. Its degradation is associated with various joint diseases, such as osteoarthritis, highlighting its importance in maintaining healthy cartilage. Understanding aggrecan's function can aid in developing treatments for these conditions.