Cartilage damage of the knee is common and may present in patients as a variety of symptoms. These conditions can be classified based on location, etiology, and/or pathophysiology. A systematic approach to the evaluation and classification of chondral injuries helps improve definitive management. The four most common types of knee cartilage damage are osteochondritis dissecans, incidental chondral defects, patellofemoral defects, and defects encountered after meniscectomy.