Drop First developed to store digital music. Later, was adapted to store digital computer data. Can be written, read many times, erased, rewritten, and has a capacity of about 650 MB. Single-sided discs can hold about 4.7 GB of data. Dual-layer discs can hold up to 8.5 GB of data. Dual-layer version employs two recordable dye layers, each capable of storing data. Uses blue laser light. which has a short wavelength, allowing data to be packed more tightly onto the disc and is rewritable. Was originally developed for high-definition video (and expanded content on movie discs), but can also be used for data storage.