A zip file works by acting as a container to transport the file. The same way that random things aren't tossed around a cargo ship–instead, they stack cargo containers to save space–sending files without first zipping them results in less available space. A zip file comes in handy when you are trying to send a lot of files through e-mail. You can't send too many, but when they are zipped, you can send more.
How Do Zip Files Work
Zip files works by doing three things. The first thing that it does is bundle files together into one file. This makes storing and organization significantly easier. The next thing that it does is it shrinks down the size of the files to a much smaller size. Typically, the files can be shrunk down 90% which makes sending many more files a lot easier. Finally, the zip file can offer another level of security. Users can add a password needed before unzipping it.
The way it works is simple. Using a program–such as WinZip–an algorithm goes in and removes all of the replaceable pieces of data. For example, the data that says a file is a Microsoft Word document is removed. That isn't necessary. However, the data that contains the text of the file won't be removed because that is the actual text. This algorithm gets rid of all that isn't needed to transport the file.
What this does is create a smaller file that cannot be used. Opening a zipped file is impossible because there aren't any of those needed pieces of data. However, using a program–WinZip again–you can add back those replaceable pieces of data to the file. When this happens, the algorithm goes in and adds the data where it needs to be so that the computer can read it.
Once this is done, you can access the file as if it were never archived. Transporting the document, though, was much easier when it was archived because you weren't uploading all of that replaceable data to the e-mail account.