Endodontic microbiology focuses on the infectious nature and the clinical treatment of endodontic pathosis. It enlightens the specific microbial species involved in pathogenesis of periradicular diseases. A better understanding of the characteristics and properties of bacteria and their biofilms along with the environmental changes, associated with endodontic disease is necessary to develop a basic understanding of the disease process and a sound rationale for effective management of endodontic infections and enhance success.