The deoxyribonucleic acid (DNA) carries hereditary codes which is translated by the cells to synthesize the ribonucleic acid (RNA) and polypeptides which can generate and perform vital function. The double helix structure is the most studied model of the DNA that was proposed by Watson and Crick. The capability of DNA to work as a genetic material can be stored and conducted during cell division to permit this information to be doubled and transmitted to the incoming generation. Any damage in the structure of DNA is an essential direct cause for the progression of cancer and other disorders. The factors for DNA damage can be classified as exogenous and endogenous factors. In this review article, we highlight the evidence-supported information about the structure, functions and clinical significance of DNA.