This modern miracle gained prominence in the late 1980's and has become the primary distribution medium for software to consumers. The Compact Disk-Read Only Memory (CD-ROM) disk itself is a collection of concentric circles containing millions of pits and plateaus which correspond to on/off bits of data. The disk is read with an optical laser similar to the one used to scan your groceries at the supermarket. Most disks of this kind are "Read Only" meaning that the computer can retrieve information from the disk, but cannot place information on it. New developments have improved this technology to allow writing and rewriting data to the disk. A different kind of hardware mechanism is needed to employ this innovation.