The article reviews the role of cellular senescence in aging and age-related diseases. Senescence, historically viewed as an irreversible cell-cycle arrest mechanism to prevent cancer, has been found to play a more complex role in various biological processes, including development, tissue repair, and aging. Recent insights suggest that senescence is a dynamic, multi-step process with diverse phenotypic states. The review discusses the causes and effector pathways of senescence, highlighting the involvement of DNA damage response, oncogenes, and tumor suppressors. It also explores the differences between acute and chronic senescence, and the impact of senescent cells on tissue function and age-related diseases. The article concludes by discussing potential therapeutic strategies for targeting senescent cells to improve healthy lifespan and treat age-related pathologies.The article reviews the role of cellular senescence in aging and age-related diseases. Senescence, historically viewed as an irreversible cell-cycle arrest mechanism to prevent cancer, has been found to play a more complex role in various biological processes, including development, tissue repair, and aging. Recent insights suggest that senescence is a dynamic, multi-step process with diverse phenotypic states. The review discusses the causes and effector pathways of senescence, highlighting the involvement of DNA damage response, oncogenes, and tumor suppressors. It also explores the differences between acute and chronic senescence, and the impact of senescent cells on tissue function and age-related diseases. The article concludes by discussing potential therapeutic strategies for targeting senescent cells to improve healthy lifespan and treat age-related pathologies.