The DNA is present in every cell of a person’s body, not only in the cell’s nucleus but also in its cytoplasm, in mitochondria. Of great importance is the fact that, except for the rare occurrence of a mutation, the DNA in every cell of the person’s body is identical. As a result, DNA can be taken from saliva, sweat, blood, hair, skin or bone cells for individual identification. The many opportunities to obtain DNA evidence can be seen, for example, in the number of places where saliva has been identified: a bite mark, an area licked, bed linens, a mask worn, paper tissue, a washcloth, a cigarette butt, a toothpick, the rim of a bottle or glass, but all of those sources are available just for present DNA. In the case of old DNA, also called ancient DNA (aDNA), the things are different and the possibilities to analyse the substrate of genetic information are limited to bone fragments or teeth. Even in these conditions, the DNA analysis is a very accurate and powerful tool for getting useful information in Archaeology.