Terahertz (THz) technology is probably best known to the public as a powerful tool for imaging, since it has been applied in security and medical scanning, resulting in numerous impressive images that would be unobtainable using other technologies. With the roll-out of 5G mobile networks, research into 6G wireless communications is heating up. It is envisioned that THz technology will be used for 6G and future wireless communications. In this paper, we review how THz technology has been employed for imaging and wireless communications, identify state-of-the-art developments in the field, and then examine and compare common devices and issues in both applications. The possibility of integrating THz imaging/sensing and wireless communications is considered, and challenges and future perspectives are presented and discussed. It is shown that THz technology is indeed a key enabling technology for both imaging and wireless communications in the future.