A new type of discs – digital videodisc (DVD) – was developed by Philips and Sony in 1995. It looks and works like a CD-ROM but can store more than 15 times as much information. Single-sided disc2 can store up to 4.7 gigabytes of data such as high-definition digital video files. A DVD has the same dimensions as a standard CD but cannot be read by a standard CD player, though a DVD player can read standard CDs. Beginning in the late 1990s, various writable and rewritable DVD formats were introduced.
Flash memory is another electronic storage unit. Since its invention in the late 1980s (by Intel and Toshiba), it has become standard for portable devices such as digital cameras, cellular telephones, PDAs, MP3 players, and video-game machines. In the early 21st century, flash memory devices that could fit on a key ring and had storage capacities of up to 1 GB (and later more) began to serve as portable hard drives.