Nucleotides are the rungs of the DNA ladder that form the information component of the chromosome. They each consist of a nitrogen base (adenine, thymine, cytosine or guanine which are abbreviated as A, T, C, and G, respectively). Adenine and thymine, for example, naturally fit together to make one rung. The nitrogen bases are attached to the deoxyribose or ribose sugar (DNA and RNA respectively) and not to each other. Thus, the order of nucleotides along the DNA polymer is completely independent of the neighbouring nucleotide. However, once there is a particular nucleotide on one strand at one position, the opposite strand must exhibit the nitrogen base that makes the pair (A with T, T with A, C with G, G with C). The fact that the order of nucleotides is independent along the chain means that the molecule is able to provide storage of complex and improbable information.
Indeed, the information content of each genome is a masterpiece of intelligent design.