As a brief explanation: Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus.
DNA consists of a pair of molecules, organized as strands running start-to-end and joined by hydrogen bonds along their lengths. Each strand is a chain of chemical "building blocks", called nucleotides, of which there are four types: adenine (abbreviated A), cytosine (C), guanine (G) and thymine (T).
In molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). In DNA, adenine (A) forms a base pair with thymine (T), as does guanine (G) with cytosine (C)