The potential advantages of digital terrestrial television broadcasting (DTTB), in terms of service quality, lower costs and programme diversity, are summarized in the introduction of this handbook. In frequency planning terms, where new or unused frequency spectrum is available, digital television coverage from individual transmitters or from networks of transmitters can be planned to achieve the full potential of DTTB. This produces considerable benefits (compared to the current analogue situation), in terms of service provision and spectrum utilization. However, the spectrum situation is far from ideal, and there are numerous problems involved in finding the required spectrum, and in dealing with its allocation and assignment, that will have to be overcome before DTTB services can become a reality in many parts of the world.