This work covers ageing from a fundamental cell biological perspective. The evolution and developmental genetics of senescence are explained clearly. All the various theories of ageing - the Hayflick limit and telomeric shortening as a possible biological clock, the impacts of somatic mutations, oxidative stress, accumulation of waste materials in cells with age - are explained and critically assessed. The author presents vivid case accounts about disorders that open windows on to the ageing process. The impacts of ageing on the brain and nervous system are given special attention, as are the effects of caloric restriction on maximum lifespan.