Secondary Storage Options
A hard disc drive stores data onto a fast-spinning disc that's covered with magnetic material onto which bands of information are recorded into tracks and sectors of code by read/write heads. This type of storage holds an incredible amount of information that can be retrieved incredibly quickly. Examples include internal and external hard drives, and cost is about $0.05 per GB.
Optical storage puts data onto discs made of layered plastic and aluminum. A laser writes data by creating a single spiral track of bumps and flats. To read the data, a laser shines light which reflects from the bumps to communicate code which is then translated to useful information. Examples include CDs and DVDs. Blank CDs cost roughly 25 cents per GB, and blank DVDs cost about 4 cents per GB.
Flash storage involves charging an oxide layer in the device with electrons which then, when sufficiently filled, gets read as part of the binary code that can be translated into useable information. Examples are Solid State Drives, Memory Cards and USB Flash Drives. USB flash drives cost between $1.50 and $4.00 per GB.