The amount of data contained in a native video or audio file can be large enough to make playing it, using it or downloading it impossible or impractical on anything but a very fast computer with enormous storage. In order to remedy this condition, large files are compressed using algorithms, which eliminate data in a way that allows the picture/sound to be decompressed back to its original form without losing any of the original information (lossless compression). When the file needs to be made smaller, more information is removed, resulting in a file that can't fully reproduce the original picture/sound information (lossy compression). To use a compressed file it must be decompressed within the hardware or software. This procedure of compressing and decompressing data by using algorithms is called a Codec.

Streaming media refers to media (video or audio) that is consumed (viewed or heard) while it is being delivered. Streaming allows a lengthy audio or video program to be transmitted over the Internet by transmitting a continuous signal in real time rather than downloading an entire clip at once. For example, most online radio is "streamed," whereas a podcast would not be considered streaming media as it is downloaded first and then consumed.

For video DVD is an unacceptable format for long-term storage, but it is an ideal format for exhibition as it is easy to use and relatively inexpensive. For simple data storage, which requires no compression (program files, etc.) DVD is an acceptable format as long as back-up copies exist. For a comprehensive discussion of storage formats and procedures, please visit the Preservation section of the Guide.

The seller should provide copies of all necessary files on a DVD or hard drive. Extensive documentation on how to install this work or run the code should also be provided. Visit the Computer-based Arts Best Practices Preservation section of this Guide for more information.

Metadata is, quite simply, data about data. A common example is catalogue material for a book in a library. It gives background information and context about the book, but doesn't contain the content of the book itself. Metadata is becoming more and more important in the digital age because it allows us to locate information more easily. Keywords are a form of metadata, and many search engines rely heavily on metadata to inform their results.

This depends upon whether or not an artwork has dedicated equipment. For some works the hardware is integral to how the work creates meaning; in others it is just a vehicle to carry the media and is highly variable. It is important to know exactly what the functional parameters are for the equipment so you can be sure to use appropriate hardware, and it is essential to communicate with the artist or artist's representative. For additional information please refer to the Articles and Preservation sections of this Guide.

Preservation, cataloging and conservation issues should be addressed at the time of acquisition to ensure the future viability and accessibility of the computer-based or digital works in your collection. In addition to issues such as documentation and data storage, preservation strategies for computer-based works might include emulation, migration, or encapsulation. For a detailed discussion of preservation guidelines, see the Preservation section of this Resource Guide.