Lost media

Lost media is any type of media thought to no longer exist in any format, or for which no copies can be located, partial or otherwise. The term primarily encompasses visual, audio, or audiovisual media, such as films, television, radio broadcasts, music, and video games. Many television and radio broadcast masters, recorded onto magnetic tape, may be lost due to the industry practice of wiping. Motion picture studios also often destroyed their original nitrate film elements, as film and broadcast material was often considered ephemeral and of little historical worth after they had made their revenue. Some media considered lost may exist in studio or public archives, but may not be available to most people due to copyright or donor restriction rules, or for the most part, complete disinterest by anyone in an outdated program or subject matter. Due to the unstable nature of any format, films, tapes, phonograph records, optical discs like CDs, Blu-ray discs, and DVDs, and digital data stored on devices such as USB flash drives, SD cards, solid-state drives, and hard disk drives, all naturally degrade over time, especially if not kept in correct storage conditions. Preservation efforts attempt to avoid the loss of works; this is usually done by storing them in archives.