The ECM has been likened to a 'glue' that binds cells together in connective tissues. In practice it is rather more than that: it’s a complex, three-dimensional network of proteins and polysaccharides, built and maintained by the very cells it surrounds. Every tissue has its own version so that the ECM of cartilage is quite different from that of skin, lung or bone, and it is this variation that gives each tissue its mechanical ‘character’ (properties). The ECM is also dynamic – being continually deposited, remodelled and broken down throughout the life of an organism, with the balance shifting during growth, wound healing, ageing and disease.