Ageing is caused by the progressive loss of structural and functional capacity in cells over time, leading to death. It is influenced 60% by genetic factors and 40% by environmental factors such as trauma, disease, diet, and stress. The main structural and biochemical changes that occur during ageing include the accumulation of oxidative damage in cells from reactive oxygen species, advanced glycation end products, and abnormally folded proteins. Telomerase plays a role in preventing shortening of telomeres during cell division. Restricting calorie intake and maintaining good health habits can help delay the cellular ageing process.