To further illustrate the challenges and opportunities for video search, this chapter will address the nature, availability, and attributes of different sources of video data. Search engines leverage all available information relevant to media and this chapter will provide details about available metadata for different types of video including electronic program guides, content identifiers, video on demand packages, and syndication standards. We will also introduce representations of textual information associated with media such as transcripts, closed captions, and subtitles. The breadth of metadata sources is described at a high level, and more detailed information is provided for selected domains including, broadcast television, digital video recorders (DVRs), consumer video, and Internet sources such as podcasts and video blogs. After media is published on the Web, additional metadata may accrue from social sources in the form of tags, ratings, or even user contributed subtitles, all of which can be exploited by video search engines to produce more accurate results.