DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person's body has the same DNA. DNA is a double helix formed by base pairs attached to a sugar-phosphate backbone.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is crucial when cells divide because each new cell needs to have an exact copy of the DNA that is present in the old cell.