The human genome is a representation of the complete sequence of genetic instructions that comprises the DNA of humans. Humans have 23 chromosomes that contain approximately three billion base pairs arranged in a particular order, giving the human species traits unique from other species.
Scientists began attempting to decode the human genome in 1990. A preliminary copy of the human genome was prepared in 2000, with a highly accurate map constructed by 2003. By mapping the genetic sequence of DNA, scientists can look for abnormalities or differences in the sequence among individuals, possibly pinpointing the cause of different diseases or disorders.