Articular cartilage (AC) is vital for the proper functioning of the knee. This smooth white connective tissue covers the joint surfaces and allows pain free movement for decades. Its high durability originates from its unique structure mainly composed of cells, macromolecules and water. The same structure allows the cartilage to transmit the load and act like a cushion in the harsh mechanical environment of the body’s largest joint. Herein, it is discussed the origin, function and structure of knee AC. After briefly discussing its embryological development, the biochemistry and the related biomechanical properties of AC are also overviewed. The tissue components will be individually described and its role in the cartilage will be explained. It is also reviewed the different mechanical behaviours of the tissue. Finally, AC tissue homeostasis and maintenance is discussed, which is still somewhat requires a deeper knowledge. The anabolic and catabolic processes, namely tissue synthesis and degradation and the involved molecules and signalling pathways are also subjects that have been addressed in the current chapter.