Secondary storage options
There are three types of secondary storage that I learned about: magnetic, optical and flash. All three do the same job, that is to store data, but they are useful in different ways.
Above is a picture of the inside of a hard disk. It works by storing data on tiny concentric circles on the disk’s surface. A magnetic film memorizes the information in the form of bits, and it stores and recovers information using this magnetism. A hard disk is useful for backing up large amounts of data, say everything on your computer. A hard disk costs around $50.00 for a 1 TB. To give you some perspective there are 1000 GB in a TB. This is by far the most cost effective choice for storing data.
The DVD R is an example of an Optical secondary storage. You may also be familiar with the music CD, video games and data disks. They all works with one spiral that contains data on the disk. It is stored as flat spots or bumps. There are layers to the CD: layer 1 is plastic, layer 2 is the data (bumps), layer 3 is aluminum, layer 4 is a protective coating of plastic, and layer 5 is the label. This option cost around a dollar per GB, which is inexpensive. However, the disks are relatively large and not practical to carry around.
A Flash Drive is a kind of transistor that stays switched on (or off) even when the power is turned off. It is controlled by a source, a drain and 2 gates. The second gate allows electricity to to travel to the first gate and this is how the transistor stores it's information whether the power is on or off. The flash drive, also known as a thumb drive or jump drive costs around a dollar for 2GB. I prefer using a flash drive for smaller data storage that I want to carry around, or easily share with someone.