  Terahertz (THz) communications have emerged as a promising candidate to
support the heavy data traffic and exploding network capacity in the future 6G
wireless networks. However, THz communications are facing many challenges for
practical implementation, such as propagation loss, signal blockage, and
hardware cost. In this article, we introduce an emerging paradigm called
intelligent reflecting surface (IRS) assisted THz communications to address the
above issues, by leveraging the joint active and passive beamforming to enhance
the communication quality and reduce overheads. Aiming at practical
implementation, we first give an overview of the currently available approches
of realizing THz active/passive beam steering at transmitter and IRS,
respectively. Based on these capabilities, we introduce a beam training
strategy for establishing joint beamforming in THz communications. Later, we
present various emerging and appealing 6G scenarios that integrate IRS into THz
communications. Finally, we provide open challenges and future research
directions for this new paradigm.
