PT Journal AU Yamamoto, H TI The International Linear Collider Project-Its Physics and Status SO Symmetry-Basel JI Symmetry-Basel PY 2021 BP 674 - 15pp VL 13 IS 4 DI 10.3390/sym13040674 LA English DE Higgs particle; elementary particles; standard theory; linear collider; dark matter; top quark AB The discovery of Higgs particle has ushered in a new era of particle physics. Even though the list of members of the standard theory of particle physics is now complete, the shortcomings of the theory became ever more acute. It is generally considered that the best solution to the problems is an electron-positron collider that can study Higgs particle with high precision and high sensitivity; namely, a Higgs factory. Among a few candidates for Higgs factory, the International Linear Collider (ILC) is currently the most advanced in its program. In this article, we review the physics and the project status of the ILC including its energy expandability. ER