This chapter aims to provide readers with a general vision of 6G. Firstly, we
give a simple overview of various aspects related to 6G, including inevitability of 6G
research, international organizations for standardization, and also 6G research progress
of some countries/regions. Then, 6G spectrum compositions are discussed in detail
with emphasis on SUB-6, mmWAVE, and Terahertz (THz).
Keywords: 6G, Frequency spectrum.
