Nanotechnology is a rapidly expanding field with its applications in biomedical sciences and is associated with the engineering and production of materials at the atomic and molecular level. Study of silver nanoparticles has a wide application in various fields. Metal nanoparticles are the most promising due to their anti-bacterial properties which, occurs because of the high surface to volume ratio. Silver nanoparticles (AgNPs) are particularly excellent because of their potential applications in health care, textile fibers, food packaging, and antibacterial fields. When used in relatively low concentrations at the same size and shape Ag-NPs are non- toxic or less harmful to mammalian tissues and environmentally friendly. In this study an overview on the synthesis of AgNPs from different sources and their antibacterial activity has been given. The physical and chemical methods and green synthesis as well as microbial synthesis of AgNPs are mentioned here. It has been shown that synergistic action of AgNPs and antibiotics have antibacterial effect on pathogenic bacteria .