Deoxyribonucleic acid (DNA) is a polymer made of two polynucleotide chains that coil around one another to form a double helix and which contains the genetic material necessary for all known creatures, including many viruses, to develop, function, grow, and reproduce. Nucleic acids include DNA and ribonucleic acid (RNA). Nucleic acids are one of the four main categories of macromolecules that are necessary for all known forms of life, along with proteins, lipids, and complex carbohydrates (polysaccharides).