Metadata is quite literally "data about data." Metadata is the information stored below the surface of computer documents, spreadsheets, or presentations. Office productivity programs, such as Microsoft Office, create this metadata online, although few users realize it is there because it is hidden. Such information can help forensic investigators to identify an employee who is improperly accessing sensitive documents, to establish links between criminal suspects, and to uncover valuable investigative information. Indeed, the case of the Wichita, Kansas BTK serial killer was solved by using metadata to link a computer disk mailed to a television station with a computer in the BTK killer's church. Contact information is presented for more details about metadata.