DNA is formed by the polymerization of four different nucleotides. These nucleotides are:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T)

Each nucleotide consists of a sugar (deoxyribose), a phosphate group, and one of the four nitrogenous bases listed above. The sequence of these nucleotides determines the genetic information encoded in DNA.