  Upcoming beyond fifth generation (5G) communications systems aim at further
enhancing key performance indicators and fully supporting brand new use cases
by embracing emerging techniques, e.g., reconfigurable intelligent surface
(RIS), integrated communication, localization, and sensing, and mmWave/THz
communications. The wireless intelligence empowered by state-of-the-art
artificial intelligence techniques has been widely considered at the
transceivers, and now the paradigm is deemed to be shifted to the smart control
of radio propagation environment by virtue of RISs. In this article, we argue
that to harness the full potential of RISs, localization and communication must
be tightly coupled. This is in sharp contrast to 5G and earlier generations,
where localization was a minor additional service. To support this, we first
introduce the fundamentals of RIS mmWave channel modeling, followed by RIS
channel state information acquisition and link establishment. Then, we deal
with the connection between localization and communications, from a separate
and joint perspective.
