Even more complex is the mode of preserving data for backup and archival purposes. For backing up and saving any data, what is requisite is a hardy backup media. Any authentic backup media should qualify certain criteria. First and foremost, it should be easily available at an economical price, so as to enable the user to store data in bulk, at a low price. A good backup media should be reasonably fast and should offer an optimum speed. Finally, any worthwhile backup media should be reliable and almost flawless. Over the years, various storage media entered the market, with their own unique set of features and abilities. The list of options was further widened with the entry of CD-R into the market, in 1979.