I am delighted to introduce the first special issue on Terahertz (THz) Wave Science, Technology, and Application. This issue contains five review and research papers, all written by former Ph.D students, Dr. Xiaofei Lu, Dr. Jingle Liu, Dr. Benjamin Clough, Dr. I-Chen Ho, and Dr. Yuting W. Chen, at the Center of THz Research, Rensselaer Polytechnic Institute. These gifted scientists and engineers are among the most brilliant students that have graduated in the THz community in the past four years. This issue covers research frontiers from THz antireflection silicon structure (Dr. Chen), remote sensing (Dr. Liu), and THz wave air photonics (Dr. Lu) to nonlinear THz wavematter interaction (Dr. Ho), and THz enhanced acoustics (Dr. Clough).