The first person to discover the structure of DNA was James Watson and Francis Crick. In 1953, they proposed the double helix model of DNA, which illustrated how the molecule's structure consists of two intertwined strands with a backbone made of sugar and phosphate groups, paired with nitrogenous bases (adenine, thymine, cytosine, and guanine). Their groundbreaking discovery was significantly influenced by the X-ray diffraction images produced by Rosalind Franklin, which provided critical insights into DNA's helical structure. Watson and Crick's work on DNA laid the foundation for molecular biology, genetics, and our understanding of heredity.