Welcome to Working with .Zip Files.
This activity introduces you to what .zip
files are, their origin, and how to work with them in Windows
A .zip file is compressed container for other files.
You can add many files to a
.zip file, which will be smaller in size than the collective sizes of the files within it.
Compression is possible because many files contain white space or bytes of
data that are all one character or have a set of characters.
By removing this white space, the file can be compressed.
Consider a text file.
A text file is made up of lots of words and lots of spaces.
Each character has a number from 1 to 255 or the size of one byte.
There's a character map called ASCII, A S C I I, which determines what characters are mapped to
what number.
Characters 1 through 128 are in the printable range and 129 to 255 are used more for
control or metadata.
That means most of the characters can be represented with four bits rather than
eight, resulting in a compressed text file being half the size of an
uncompressed one.
A .zip file is a file where the data has been compressed.
Now let's take a look at the origins of .zip files and, also, how to work with .zip files in Windows.
Zip files were invented before Windows became popular.
In 1987, Phil Katz introduced the DOS based archival tool called PKARC, which
compressed files into a .ARC file very similar to .zip files.
PKARC was an improvement on a DOS program called arc,
which was written in 1985 by Thom Henderson.
ARC was the first zip-like program for the PC to become famous.
It was used to compress files that were uploaded and downloaded to and from BBSes, or
bulletin board systems.
PKARC was faster than ARC because it was written in assembler.
It was an instant hit.
Henderson, who had created PKARC sued Katz.
Katz had taken his PKARC source code
and added in data compression algorithms.
He renamed the product PK zip
.Zip was invented to save money
Katz was looking for a way to shorten the amount of time it took to transfer files.
In order to transfer files, most people were dialing into BBSes and
would be charged long distance phone rates.
The longer the time spent on the line,
the more money it would cost, so by compressing files it took less time and
money to transfer the files.
Katz never made a lot of money from PKZip, but the zip
format was so popular that it has dominated to this day.
Today, .zip files are mainly used to group many files together and the compression
feature is seen as a nice bonus.
.Zip files are for transport and storage only.
You can not and should not open and work with files directly inside a .zip file.
Rather, you should unzip first, use the files, and then copy them back into the
original zip file or create a new .zip from the edited version.
The easiest way to create a .zip file in Windows is by using the File Explorer,
which you can get to by pressing the Windows key + e.
You can create a .zip
file from any file or even an entire folder, by right clicking it and
selecting send to and then compressed or zipped folder.
You can add more files to a .zip file by simply dragging and dropping files onto it.
If the file needs to be nested somewhere in a folder within the .zip,
there's another step you need to do first.
.Zip files are hierarchical just like folders. Double-click on a .zip file to
open it up in the file explorer and you can navigate the hierarchy just like a file folder.
Once you get to the folder you want, you can drag and drop files into it.
To remove a file, just double-click on the zip, navigate to the file you want
to remove, right click on it, and select delete.
There is one very important step you must do before you extract files from
any .zip that you have downloaded from another computer or off the internet.
That step is unblocking.
By default, Windows is hostile to .zip files that come from other computers.
They can contain malware and other nasty things.
That said, Windows gives you a chance to prove that a downloaded .zip is safe.
To unblock a .zip, right click on it and select Properties.
In the property window, you will see an unlock button, simply press it.
Now comes the easy part.
To extract the files in a .zip file, you can do it the
hard way, by double clicking on it,
navigating to the file or files you want to extract, and dragging and dropping
those files in a folder somewhere.
Or you can do it the easy way, by right clicking on the .zip file and selecting extract all.
This will create an entirely new folder.
You get to choose where, containing the
uncompressed contents of the .zip file.
In this learning activity we learned what a .zip file is, the origins of .zip
files and how to work with zip files in Windows.