This paper describes application areas, elemental technologies, and the feasibility of terrestrial terabit wavelength division multiplexing (WDM) transmission systems based on super-dense wavelength division multiplexing (DWDM) technologies with a channel spacing of 12.5 GHz. Numerical simulation results quantitatively show that the merit of super-DWDM transmission is the elimination of the need for dispersion compensation over the several hundreds of kilometers of standard single-mode fiber (SMF). To support super-DWDM transmission, the prototype of a multiwavelength generator, which consists of just an intensity modulator and a phase modulator, is developed as a small-size WDM light source with high-wavelength stability. We use this prototype to conduct a 1.28-Tb/s (512 channels × 2.5 Gb/s) transmission experiment with a channel spacing of 12.5 GHz over 320 km (80 km × 4 span) of standard SMF without dispersion compensation. The potential and the feasibility of super-DWDM transmission with a channel spacing of 12.5 GHz for terrestrial systems is confirmed by the numerical simulation and the transmission experiment.