Viruses are evolved to efficiently introduce genetic material into cells.

“viruses and there are many kinds of viruses they are little bits of biology that basically exist to get dna and rna into cells and so they have a little bit of this genetic code material dna or rna and they have that encased in a coating that might have some lipids or fats and some proteins and then that floats through a liquid floats through the air hits a cell and fuses with the cell gets the dna or the rna into the cell and then that triggers the creation of new virus particles and then that's how the virus spreads so viruses are professional introducers of genetic material in the cells they are extremely good at that they are evolved for that”