This is the newest kind of memory. It uses the very latest technology. Because there are no moving parts as there are with hard and floppy disks, data stored on flash memory is much harder to destroy. Flash memory is not only used in your computer, but also in your PDA - personal digital organizer - your mobile phone and many other gadgets. Most computers need a reader attached to a USB port to read flash memory.

Here are some of the more common types of external storage:
Compact flash
- used in many cameras. Compact flash storage can be up to many gigabytes in size.

SD
- is used in many music players because SD cards have technology that helps with DRM (digital rights management) which allows the owner of the song to control where it is played.

Flash keys
- are keys with flash memory and readers built in, so they can be put into the USB port of any modern computer and laptop.

This is a hard disk drive, or HDD. It is called a hard disk drive because it is not floppy! Originally these data storage devices were called Winchesters after a successful early model. The first hard drives cost thousands of pounds and held about 10mb of data. Most modern hard drives cost under £200 and hold can hold hundreds of gigabytes.

internal hard disk
most hard disks live inside your computer and talk to the rest of your system through an IDE or SCSI connection.

external hard disk
some hard disks live outside a computer, and are attached by USB or firewire. These hard disks are very useful for carrying data between computers. some very small hard disks are being developed for use in other machines such as cameras.

Optical storage is when a plastic disk is marked, and a reader can translate those marks into 1s or 0s (bits) Optical storage is better than magnetic storage (hard disks) because it cannot be destroyed by electricity or magnetism. In fact with a ROM - read only memory - disk, the only way to destroy the data is to destroy the disk.

CD-ROM
These are the original optical media and hold 640mb of data. The earliest CDs had little holes burned into their surface with a laser, with the holes and the spaces between them making up the 1s and 0s.

CD-RW
This is a re-writable CD. Re-writable CDs were created by using a dye which changed when the laser hit it, but which could also be changed back.

DVD
There are many kinds of DVDs (Digital Versatile Disks). They use almost the same technology as CDs but they make the 1s and 0s much closer together by using light with short wavelengths. Ordinary laser light is too wide for these disks, which use x-ray lasers to work. The reason that there are so many kinds of disks is because every manufacturer has his own ideas of how to make DVD technology work, and though every idea works, some kinds of DVD can't be read by machines that are built for another kind.

Sometimes you do not want to have your data on one computer, but to have it on a central computer. Then wherever you are, you can contact that computer and ask it to send your data to you. This can happen on a proivate network on in 'the cloud'. (see below)

Server
This is a computer which has the job of passing out data on its hard disks to computers that ask for it. Trying to get information out of a server when you are you are not allowed to see that server is called 'hacking' or 'cracking' the server.

NAS
Is network attached storage. This is because not all networks (groups of computers) need a server to hold their data. Instead they use NAS which is like a large external hard disk which is used by everybody.

Internet 'The Cloud'
The internet is simply a huge network of servers. The data you are reading now is stored on a server somewhere in England. Many people keep a lot of their data, especially their emails and photographs, stored in the cloud so that they can find them wherever in the world they are.