Flash memory is a type of non-volatile storage. It retains its information even without power. So it is ideal for devices such as cameras, solid state drives and so on.
How is it different to other types of storage?
Optical storage devices such as DVDs use light to store data. The data is burned by laser beam onto the DVD surface causing small dark pits to appear that represents a data bit. The absence of a dark pit in a location is the opposite bit.
Hard disks and magnetic tape make use of magnetism to store data. Flash on the other hand makes use of electrical effects to store data. It is a 'solid state' technology because it is based on a silicon crystal slice and metal layers. There are no moving parts.
What are the advantages?
1. Flash is very tough and will not break when dropped or exposed to heat (it is a solid-state device)
2. It is very reliable as there are no moving parts, the data should be held for decades.
3. It is very compact and can store gigabytes of data in a small space.
4. It is very fast. As there are no moving parts needed to get to the data it is much quicker than hard disk or DVD.
What are the problems?
1. Data can only be stored in chunks, typically 512 to 2048 Bytes at a time. This means it is fine as a secondary storage method, just like floppy disks, hard disks and DVD's but it is no good as main memory like RAM and ROM which need byte-level access.
2. It does wear out over time. You can write to it roughly a million times before it begins to fail. In practice this is plenty for most applications.
What uses Flash technology?
It can be found in many forms
Camera memory cards
Solid state hard drives.
What about the future?
The cost and reliability of flash memory has improved enough to make it practical to use as part of a hard disk. These are called SSD Hard Drives.
These have a few Gigabytes of Flash inside that store the most often used data, whilst the spinning hard disk stores all the rest. This means that the data can be accessed really quickly as Flash is far quicker than the mechanical hard disks.