The principal element that makes up the backbone of DNA is phosphate. The structure of DNA consists of a double helix, where the backbone is formed by alternating sugar and phosphate groups. These phosphates link with the sugar (deoxyribose) of neighboring nucleotides, creating a strong and stable framework. This backbone provides structural integrity, allowing the nitrogenous bases to pair correctly for genetic coding. The arrangement of these bases encodes the genetic information essential for all living organisms.