As the archival horizon moves forward, optical media will become increasingly significant and prevalent in collections. This paper sets out to provide a broad overview of optical media in the context of archival migration. Author Alex Duryee begins by introducing the logical structure of compact discs, providing the context and language necessary to discuss the medium. The article then explores the most common data formats for optical media: Compact Disc Digital Audio, ISO 9660, the Joliet and HFS extensions, and the Universal Data Format (with an eye towards DVD-Video). Each format is viewed in the context of preservation needs and what archivists need to be aware of when handling said formats. Following is a discussion of preservation workflows and concerns for successfully migrating data away from optical media, as well as directions for future research. This is a PDF version of an article that originally appeared in the online Code4Lib Journal, Issue 24, 2014-04-16, ISSN 1940-5758.