Bacterial pathogens have a major role in human disease and cause different symptoms in all human organs. In 21 century antibiotic resistance is widespread and causes mortal disease. Phages or bacteriophages are kinds of viruses that attack bacterial cells and are ordered into one phylum which is divided into three families: myoviridae, podoviridae, and siphoviridae. Phages have a triple role including (1) pseudovirion (bacterial gene in virus envelop that delivered pathogen gene), (2) virus that eliminates the bacterial cell, and (3) silent infection. Phage has three major sections: Head, neck, and tail. The attack begins with the attachment of the virus to the bacterial cell surface. The most phage receptor is presented in cell surface and has many roles in different bacteria. On the other hand, phage should be pure and removed all contamination to avoid an immune reaction. Phage can only affect bacterial cells and don't have collateral damage to eukaryotic cells. In addition, phage display is a hopeful method for treatment, detect and cure of many diseases. In this review, we try to show the role of phages in treating some diseases and detection by phage display method.