Chapter 2 Galactic Gamma-ray Sources *Supported by Key Research and Development Project (2018YFA0404204, 2016YFA0400804), the National Natural Science Foundation of China (11905043, 11803011, 12173018, 12121003, 11773014, 11633007, U1931204, U1731136), the Original Innovation Program of the Chinese Academy of Sciences (E085021002), Guangdong Major Project of Basic and Applied Basic Research (2019B030302001) and science research grant from the China Manned Space Project (CMS-CSST-2021-B09). (1st March 2022)