Type VI secretion system (T6SS) is a class of sophisticated protein delivering apparatus, usually composed of 13 core components with or without accessory proteins in different species, involved in mediating antagonistic or synergistic communications between bacteria and/or bacteria and eukaryotes. Here, we have organized information derived from the reported literature of T6SS gene cluster, T6SS regulator (T6SR), accessory protein (T6SA), effector (T6SE), immunity (T6SI) and structure protein, together with tools for T6SS classification and T6SS predition as the web-based resource SecReT6 (Type VI Secretion system Resource) 3.0 version. More...