Where can DNA be found other than the nucleus?

DNA (deoxyribonucleic acid) is the 'language' that genes are 'written in'. The DNA in the nucleus composes the genome (complete set of genes) of the organism to which the cell belongs. Thus the human genome is the genome of the DNA within the nucleus of human cells.

But DNA, in plants and other photosynthetic eukaryotes, is found composing a completely different genome within the chloroplasts. And in most eukaryotes including animals, plants and fungi, their is also a separate mitochondrial genome composed from DNA in the mitochondria. The theory of endosymbiOSis explains the presence of DNA in mitochondria and chloroplasts.