Look at how much space different data requires.
Note that even the smallest files reserve 4096 bytes.
Data Compression: Reducing redundancy, for instance by replacing subsequences that occur more than once by reference to it. Use Lempel and Zivīs adaptive dictionary-based algorithm.
Example: The original file:
"Ask not what your country can do for you -- ask what you can do for your country"
(for simplicity we assume that no numbers occur in the file. compare "www.howstuffworks.com")
The zipped file: "1=ask, 2=what, 3=your, 4=country, 5=can, 6=do, 7=for, 8=you//
another zipped file: "1=ask_, 2=what_, 3=you, 4=r_country, 5=_can_do_for_you//
Zip the files and see how much you can gain for each.
How much file reduction can you achieve?
Compression is not only useful for storage but also before communicating/transfering data
Here is a page comparing certain compression programs, here is another good page on compression, and here is one about kids inventing a new compression algorithm. Here is a list of three freeware zip programs