CD-ROMs are optical discs that can store digital information that can only be read from, not written to or erased. They are accessed by inserting them into a disc drive connected to a computer. CD-ROMs can contain a variety of file types like documents, presentations, spreadsheets, as well as software, photos, videos and other data. Information is burned onto blank CD-ROMs using recording software that copies files and writes them to the disc in an organized format.