Silver has a long and intriguing history as an antibiotic in human health care. The bactericidal activity of silver is well documented. Earlier colloidal silver was used, however with the development of nanotechnology, silver nanoparticles were synthesized which has many fold advantages over the colloid silver. Silver nanoparticles have the ability to penetrate bacterial cell walls, changing the structure of cell membranes and even resulting in cell death. hey can increase the permeability of cell membranes, produce reactive oxygen species, and interrupt replication of deoxyribonucleic acid by releasing silver ions. Therefore these particles can kill drug resistant bacteria most effectively. The antibacterial activity of silver nanoparticles is not only size—but also shape-dependent.