The primary genetic material in living organisms is DNA, or deoxyribonucleic acid. DNA holds the genetic instructions crucial for the development, functioning, growth, and reproduction of all known life forms. It is composed of nucleotide sequences that encode genes, which in turn guide the synthesis of proteins. DNA's double-helix structure, discovered by Watson and Crick, allows it to replicate accurately during cell division. Understanding DNA is fundamental in fields like genetics, molecular biology, and biotechnology.