What Are Storage Devices?

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An understanding of storage devices and the purposes they serve makes it possible to get the most out of your computer. Most people think of a storage device as an external hard drive that you can copy data and files onto for backup or other purposes. However, that is only one type of storage device. Others, both inside and outside your computer, are used by the computer to function properly and by you to store personal files, folders and documents, including music, images and videos.


Onboard Memory Storage

The main type of memory used by a computer is connected to its central processing unit. This includes RAM (random access memory), ROM (read-only memory) and the cache, all of which are central to the main functioning of your computer. This isn't what most people mean when referring to a storage device, but these elements are critical to the functioning of the computer.

Hard Drives and Solid-State Drives

The data on your computer is stored on a hard drive or solid-state drive. Hard drives work by using a read/write head to encode information onto a magnetic disk that spins rapidly. A hard drive disc is similar in appearance to a vinyl record, except much smaller, and it rotates much more quickly. Most computers use hard disks to store your files, folders and other media.


Solid-state drives have replaced hard drives in some computers. They serve the same purposes as hard drives but do so without having any moving parts. Because of the lack of moving parts, solid-state drives are less likely to malfunction. As solid-state drive prices come down, they are replacing hard drives in some computers.

If you have a Mac, you may have a fusion drive, which is Apple's combination of a traditional hard drive and a newer solid-state drive. The computer manages the fusion drive, so that recently used information is stored on the solid-state portion of the drive, and the older information is maintained on the hard drive.


External Drives

External hard drives are what most people think of as storage devices. These are just like the hard drive or solid-state drive inside your computer, except they are portable and connect to your computer using a USB port. They usually store large amounts of data and files and are good choices for backups. Solid-state external drives tend to be more expensive than external hard drives, but they are faster and more durable than traditional hard drives.

Optical Discs

Optical discs come in the form of DVDs, CDs and Blu-ray discs. Optical discs rotate during operation while a laser reads and writes the disc content. These are often used to store music and video files, and many computers and laptops include an optical disc drive of some sort. Computers without optical drives can still make use of them through an external optical drive reader. Blu-ray discs have the largest capacity of the optical discs, storing up to 50GB of data.


Removable Storage Devices

Removable storage includes USB flash drives, SD cards and older technologies such as the floppy disk. These are mainly used to store files you need to transport from one computer to another. Floppy disks use magnetic storage, similar to hard disks, but USB flash drives and SD cards use flash memory, which is an electrical storage medium that doesn't include any moving parts. These are similar to solid-state drives but much smaller.

USB flash drives – also called memory sticks, thumb drives, USB sticks and pen drives – are popular removable storage devices that plug into the USB port of a computer and store information electronically. They come in a range of capacities, from 32GB or smaller right up to 512GB or even 1TB. These are both affordable and easy to transport.