This article presents the joint EU-Japan project THoR to demonstrate terahertz ultrahigh data rate backhaul and fronthaul applications at 300 GHz. The THoR chipset is 802.15.3-2023 compliant. The article presents an overview of the available spectrum and relevant aspects of the IEEE 8.2.15.3-2023 Standard for Wireless Multimedia Networks, the link characteristics, antenna requirements, hardware design, and simulation and link planning algorithms. The demonstrator hardware implemented four 5 Gb/s channels in a parallel bidirectional link. Laboratory bench demonstrations achieved 64-QAM modulation and 11.1 Gb/s simplex data rates per channel operating in FDD mode over 0.5 meters. The real world long distance 150 meter demonstration operated at 16-QAM modulation with 8.64 GHz instantaneous bandwidth and a link CINR of 17-19 dB for a net 2x20 Gb/s data rate sustained for three weeks.