Bacteriophages are viruses attacking the bacteria, they do not attack our cells. However, they might be of great help to us when fighting bacteria that can attack humans. Bacteriophage described here has a double stranded DNA and infects the bacteria named Echerichia Coli. The DNA is packed inside the icosaedral head of the virion. From the head protrudes the contractile tail that terminates in a baseplate from which originate 6 fibers or "legs". The bacteriophage is very effective - just a single one is enough to infect the host bacterial cell.