If you were born before the Internet and enjoy music, then you probably remember listening to Compact Discs, enabled by ISO 9660.

Although the CD has been largely overtaken by formats that work better for streaming and online purchase, it created a revolution that went beyond audio. With the ability to store much more information than most computer hard drives at the time, and the invention of technology that allowed users to 'burn' their own CDs, it quickly became a popular option for data storage. With a standard CD holding almost a million bytes of information, options for how to place files on the storage track that spirals across the disc surface were almost limitless. As a number of different structures competed, it became clear that a standard system was needed to organize the data.

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From High-Sierra to International Standard

In 1985 many of the major tech players, including Apple, Sony and Microsoft, came together at the High Sierra Hotel in Lake Tahoe, California, with the goal of agreeing an industry-wide file structure. The High Sierra Group, as they named themselves, developed a proposal that was released the following year.

This created the basis for a standard that was submitted to, and published by, Ecma international, one of a number of organizations in cooperation with ISO. Submitted to ISO's fast-track process, it was rapidly developed into ISO 9660, which was published in 1988.

The International Standard specifies, among others

  • the attributes of the volume and the descriptors recorded on it,
  • the relationship among volumes of a volume set,
  • the placement of files, and
  • the attributes of the files.

ISO 9660 has given rise to popular use of the term ISO-image, where it is used to refer to an exact snapshot of a disc. Today, the use of ISO images goes beyond their use on actual CDs. For example software, including open source operating systems such as Linux, are often downloaded and transferred to a storage medium such as a USB key using an ISO image. This enables the creation and preservation of perfectly intact file structure.