Several different types of mass storage devices exist, including hard drives, solid state drives, optical disks, floppy disks, flash drives, and other pieces of technology such as MP3 players and secure digital (SD) cards. Most types of storage devices can be used to store any type of file, but the ones in MP3 players can only display certain types of file if not connected to a computer. All of the mass storage devices require a computer to function properly, because a computer is needed to move files to and from the storage devices.
Hard drives are amongst the most common types of mass storage devices. Most computers have a hard disk drive already built into them, and they can offer a large amount of memory which can be accessed easily by the user. Universal serial bus (USB) portable hard drives are also available, which offer the storage of a hard drive in a more transportable form. Most hard disk drives use magnetic discs which store data as a magnetic pattern. Solid state drives are essentially an alternative type of hard disk drive which work faster, more quietly, and last for longer.
Optical disks are another of the most commonly used storage devices. An optical disk is better known to most people as a compact disk (CD) or digital versatile disk (DVD), which has data "burned" onto it by a laser. Most computers come equipped with a CD/DVD drive which can also write data onto the optical storage devices. This functionality has made optical disks common types of mass storage devices, and the data can be read by a variety of devices. For example, music stored on a CD can be played by most stereo systems, depending on the file format.
Floppy disks are an older class of mass storage devices, and while some computers can still play them, optical disks are much more popular. The memory of floppy disks is considerably lower than that found on optical disks and hard drives, but they are generally much cheaper to purchase and easily portable. Another advantage of floppy disks is they are universal, but they unfortunately run quite slowly, especially when compared to other devices.
Other technology such as MP3 Players and digital cameras can be used as mass storage devices. Most digital cameras use SD cards, which can feature a large amount of storage space, at least surpassing that of a CD or DVD. SD cards can usually display photographs and videos when plugged into a digital camera. MP3 players often have a great deal of memory, and can play music files without help of a PC after they have been transferred.