The fixed joints, also known as the fibrous or removable joints, the synovial joints, as well as our cartilaginous joints. So what exactly is cartilage? Well, cartilage is a type of connective tissue that consists of cells known as contracytes, as well as the extracellular matrix. And the extracellular matrix of this cartilage is made up of three types of substances. We have the collagen fibers, we have elastin fibers, and we have proteoglycans. So proteoglycans are proteins that contain our sugar components.