DNA stands for deoxyribonucleic acid. It is the macromolecule that contains the genetic information for any individual of any species of plant or animal. DNA is sometimes referred to as the “blueprint of life” because it stores the information necessary for the passage of genetic attributes to future generations. It is the chemical substance contained in cells, which determines each person's individual characteristics. A person's DNA is unique except in cases of identical twins. DNA is a powerful tool used in solving crime because each person's DNA is unique. DNA is used to identify people involved in the commission of a crime. The DNA gathered at a crime scene can either link a person to the evidence or eliminate that person. DNA is found in blood, skin cells, hair, saliva, mucus, perspiration, fingernails, semen and urine.