Many of us have downloaded mp3 or iTune tracks off of the internet. Many of us have streamed audio from the internet. Most of us have experienced the power of Dolby Sound either at home or at the theatre. The common enabling thread of these and numerous other technologies that we unknowingly encounter on a daily basis is digital data reduction or compression. Few of us really understand the underlying principles that enable these technologies that many of us have so fully embraced. At Electronic Musician there is a great article on the subject of Digital Data Compression. The wide variety of compression standards presents a veritable alphabet soup of acronyms and trade names, Dolby AC-3, Sony Atrac, Roland R-DAC, DTS, MP3, MP4, etc. So what are they and why are they used. Fidelity in digital audio is a function of the sampling rate and resolution of the digitization process. However, as sampling rate and resolution increase the data rate and storage space also increase. Transmission of the highest quality audio without compression would require massive amounts of bandwidth.