Digital audio broadcasting refers to the transmission of audio signals in a digital format. There are several synonyms for this term which are often used interchangeably. Some of these include digital radio, DAB, digital audio radio service, and high definition radio. Digital radio and DAB are among the most commonly used synonyms for digital audio broadcasting, especially in countries where DAB is the preferred transmission standard. Similarly, digital audio radio service (DARS) is another term used predominantly in North America to refer to digital broadcasting. On the other hand, high definition radio (HDR) is a term used to describe the superior sound quality of digital radio signals.