Deoxyribonucleic Acid is a nucleic acid that carries the genetic information of almost all living organisms. The blueprint of life is recorded in the arrangement (base sequence) of four bases contained in DNA; they are A (adenine), T (thymine), G (guanine), and C (cytosine). The DNS base sequence is aligned in a double helix structure in the cell nucleus, and each set of two facing bases forms a pair. These two bases are called "base pairs". There are thought to be approximately three billion base pairs in the human nuclear genome. That volume of information is said to be equivalent to the amount of text in a morning paper published over a period of 25 years.

In the DNA base sequence there are genetic regions and regions whose function cannot be identified. The genetic regions contain information on protein structures, timing for making protein, and the information required for the DNA to replicate itself. If the genetic region receives external stimulation, the DNA is transcribed and translated into proteins. The region whose function cannot be identified is called "junk DNA" and was considered to be useless. However, since the beginning of the 21st century, junk DNA has also been thought to contain essential biological functions.