All About ZIP Files

The current version of this document can be found on-line at: http://www.eurekais.com/brock/aazip.htm
Looking for other versions of the ZIP file tutorials? Click here.
Last Updated: November 27, 2001
- Download and Install PKzip for Windows Version 2.70
- Unhide File Extensions in Windows
- Download a ZIP File From the Internet
- Unzip a ZIP File with PKzip for Windows
- Installing and Starting GreenFace
- Creating ZIP Files that "Span" Multiple Disks
- Creating Self-Extracting ZIP Files
- Creating Password-Protected ZIP Files
- Setting the Compression Level
Why ZIP Files? Many files which are available for download on the internet are stored as "ZIP" files. A ZIP file is a "compressed" format file. One or more original files can be compressed in size and then stored in a ZIP file. When the original files are needed, the user can "extract" the original files from the ZIP file using a ZIP file program. Storing files in the ZIP format provides two advantages for the person who downloads the file: (1) Several files (e.g., all of the files associated with a particular program) can be downloaded as one file, and (2) the files stored in a ZIP file are compressed, making the ZIP file smaller than the size of the uncompressed files, resulting in a faster download. The amount of compression varies depending on the type of original file being compressed. Word processor and database files often compress down to as little as 10 percent of their original size. Other types of files, such as some graphic image files, compress very little. When working with different types of files, an average of about 50 percent compression is typical.
ZIP File Programs. There are several programs that manage ZIP files for you. Using a ZIP file program allows you to extract the original files from a ZIP file and to create your own ZIP files. The first ZIP file program was "PKzip for DOS," by the late Phil Katz, the inventor of the ZIP format. It was written for the obsolete DOS operating system that runs on IBM-compatible computers. The tutorials in this web site will focus on PKzip for Windows, a Windows 95/98/NT program. PKzip for Windows comes in two versions: A licensed version that you must pay for and a shareware version. In this tutorial, we will use the shareware version.
Unzipping ZIP Files. The process of extracting the original files from a ZIP file is known as "unzipping" the ZIP file. Due to the many requests for guidance I have received from internet users who are unfamiliar with ZIP files, I have created a step-by-step tutorial (see part III) that explains how to use PKzip for Windows to unzip ZIP files. This web site also contains a tutorial on how to create your own ZIP files (see part IV). For information on advanced ZIP file topics, such as how password protect your ZIP files or how to create a ZIP file that spans multiple floppy disks, see part V of this tutorial.
How to Recognize a ZIP File. You can recognize a ZIP file by its file name extension of ".zip". For example, the file, "yowza.zip", is a ZIP file because the file's name ends in ".zip". (For more information on file name extensions, see part III, B, below.) Some ZIP files are "self-extracting," and will have a file name extension of ".exe". See part V for more information on self-extracting ZIP files.
What About Winzip? Why does this tutorial focus on PKzip for Windows instead of Winzip, another popular ZIP file utility? The answer is that I "grew up" using PKzip and I thus know how to use PKzip for Windows better than I know how to use Winzip. If you prefer to use Winzip for your ZIP file needs, you can find out more about Winzip at http://www.winzip.com.
This section of the tutorial details the changes I have made to the tutorial since the last edition.
This is the first major rewrite of the tutorial since May of 2000 and quite a few things have changed. Since the May 2000 edition, I have:
- Replaced the broken link to PKzip for Windows 2.70 with several working links.
- Replaced the broken link to the outdated Wintrek game with several new links to the "GreenFace" game.
- Corrected several unclear passages and several typos.
- Rewritten portions of the tutorial so that the steps provided will work under Windows 95, Windows 98, Windows ME, Windows NT, and Windows 2000. Sometimes this need for compatibility requires me to show only the "long way" to do something, avoiding the use of shortcuts that may exist in a particular version of Windows. In addition, I test the tutorial only under Windows 2000, so if you see a step in the tutorial that doesn't work under your version of Windows, please let me know by sending e-mail to "bwood@eurekais.com".
- Added more screen shots to make following the steps in the tutorial easier to do.
III. How to Unzip ZIP Files with PKzip for Windows | Go to Top |
Provided below is a "quick and dirty" guide to unzipping ZIP files with PKzip for Windows. This guide is designed to help novice ZIP file users quickly and easily extract the original files from a compressed ZIP file. Many useful programs, including computer utility programs, games, screen savers, and the like are distributed as ZIP files.
(Note: This tutorial was designed for users of Windows 95, Windows 98, Windows ME, Windows NT, and Windows 2000. If you use Windows XP, the steps in this tutorial will *probably* work for you but are not guaranteed as the tutorial has not been tested under these versions of Windows.)
A. Download and Install PKzip for Windows Version 2.70
These download instructions are designed for users of Microsoft Internet Explorer 5.x. If you use a different version of Internet Explorer, or if you use Netscape or another web browser, the procedures will be similar but not exactly as presented here.
- "Point" your web browser at one of the sites below. If you are using this tutorial on-line, just click on one of the links. If you are using a printed copy of the tutorial, type one of the URL's below into the Address box in Internet Explorer and hit the Enter key.
(Note: If the site you picked is slow or does not respond, try a different one.)
ftp://ftp.uni-magdeburg.de/pub/mirror/win95/winsock-l/Misc_Utils/Compression/pk270wsp.exe
ftp://ftp.archive.de.uu.net/pub/winsock-l/Windows95/Misc_Utils/Compression/pk270wsp.exe
ftp://ftp.cuhk.edu.hk/pub/pc/windows/winsock-l/Windows95/Misc_Utils/Compression/pk270wsp.exe
ftp://ftp.rediris.es/mirror/winsock-l/Windows95/Misc_Utils/Compression/pk270wsp.exe
ftp://ftp.nl.uu.net/pub/winsock-l/Windows95/Misc_Utils/Compression/pk270wsp.exe
ftp://ftp.singnet.com.sg/pub/winsock-l/Windows95/Misc_Utils/Compression/pk270wsp.exe
- When prompted, click on the Save this program to disk radio button.
- Click on OK. Here is a snapshot of the window as you click on OK:

- When the Save As window appears, type this into the File name: dialog box:
c:\windows\temp\pk270wsp.exe
(Note: If you are using Windows NT or Windows 2000, substitute "winnt" for "windows" in the line above.)
- Click on the Save button. The PKzip for Windows installation file will now download to your computer. The file is about one megabyte in size. If you have a slow connection to the Internet, the download could take several minutes to finish. Please be patient.
- When the file has downloaded, click on the Start button.
- Click on Run. The Run window opens.
- Fill in the Open: dialog box with:
c:\windows\temp\pk270wsp.exe
(Note: Again, if you are using Windows NT or Windows 2000, substitute "winnt" for "windows" in the line above.)
- Click on OK.
- The PKzip for Windows installation program will now start. Follow the prompts and use the default settings. When the installation program is finished installing PKzip for Windows, you may close the PKware window that the installation creates and leaves open. To close the PKware window, click on the "close" button in the upper right hand corner of the PKware window. The close button looks like this:

- Congratulations, you have successfully installed PKzip for Windows!
B. Unhide File Extensions in Windows
Before we go any further with this tutorial, I want to take care of one my pet peeves with Windows. By default, Windows *hides* file name "extensions." This means that when you look at a file in the Windows Explorer, you see the icon for the file and the name of the file, but you do not see the file's *extension* (the extension is everything after the "dot" in the filename). Extensions are important because they tell you what type of file you are looking at. For example, a file with a ".exe" extension is a program file. A file with a ".zip" extension is a ZIP file. A file with a ".doc" extension is a Microsoft Word file, etc. With the extension of a file hidden, you have to recognize what kind of file the file is by looking at the icon, something I can never remember.
Here is how to "unhide" file extensions in Windows 95/98:
- Click on the Start button.
- Click on Settings.
- Click on Folder Options....
- Click on the View tab.
- Look at the checkbox next to Hide file extensions for known file types. Does it have a check in it? If so, click on the checkbox to remove the check. If it doesn't have a check in it, leave it alone.
- Click on OK.
- You have now "unhidden" file extensions in Windows.
Here is how to "unhide" file extensions in Windows 2000:
- Click on the Start button.
- Click on Settings.
- Click on Control Panel.
- Double click on Folder Options....
- Click on the View tab.
- Look at the checkbox next to Hide file extensions for known file types. Does it have a check in it? If so, click on the checkbox to remove the check. If it doesn't have a check in it, leave it alone.
- Click on OK.
- You have now "unhidden" file extensions in Windows.
C. Download a ZIP File From the Internet
Once you have installed PKzip for Windows, you can test it by downloading a ZIP file from the internet and unzipping the file. Here are several links to a ZIP file (GFace12.zip) you can download:
ftp://ftp.univie.ac.at/mirror/WinSite/win95/games/GFace12.zip
ftp://ftp.rediris.es/mirror/winsite/win95/games/GFace12.zip
ftp://sunsite.cnlab-switch.ch/mirror/winsite/win95/games/GFace12.zip
ftp://ftp.ntua.gr/pub/pc/winsite/win95/games/GFace12.zip
ftp://ftp.agt.net/pub/winsite/win95/games/GFace12.zip
ftp://ftp.monash.edu.au/pub/win95/games/GFace12.zip
The GFace12.zip file contains the files associated with the "GreenFace" shareware computer game. GreenFace is a fun arcade game based on the venerable "Pac Man" of the early 1980's. The graphics have been improved and the game features 9 levels of action. The game runs under Windows 95/98/ME.
- To download the GFace12.zip file, just click on one of the links above (or point your browser at it, if you are working from the printed version of this tutorial). The File Download window will pop up. Click on the Save this file to disk radio button.
(Note: If the site you picked is slow or does not respond, try a different one.)
- Click on OK. The Save As window will pop up.
- Click on the View Desktop icon. The View Desktop icon looks like this:

- Click on the Create New Folder icon. The Create New Folder icon looks like this:

- Type in "gfinst" (without the quotes) as the name of the new folder (the folder name is short for "GreenFace install files"). Hit the Enter key to finish typing the name of the folder. An empty folder called "gfinst" now appears in the Save As window.
- Double click the "gfinst" folder to open the folder.
- You are now looking at the contents of the "gfinst" folder (it is empty). Click on the Save button to download GFace12.zip into the "gfinst" folder. The file size of GFace12.zip is approximately 3.4 megabytes. If you have a slow connection to the internet (such as a 56K or 28.8K modem) the file may take a few minutes to download. Please be patient. When the download is finished, the Save As window will close.
(Note: Under some versions Internet Explorer you may have to click on the Close button to close the Save As window.)
- That's it! You have downloaded a ZIP file from the internet.
D. Unzip a ZIP File With PKzip for Windows
Let's take the GFace12.zip file we downloaded in section C, above, and unzip it using PKzip for Windows.
- Look at the Windows desktop. Look for the "gfinst" folder you created on your desktop in section C. See it? Good. Double click the "gfinst" folder to open it.
- There should be one file in the "gfinst" folder, GFace12.zip. Double click GFace12.zip to open it with PKzip for Windows.
- When you open GFace12.zip with PKzip for Windows, you will see the compressed files inside of GFace12.zip. The window will look something like this:

- To extract the files inside of GFace12.zip, click on Extract and then Extract files.... The Extract window will appear.
- Look under the "Extract to" section of this window. See the radio button labeled Disk? Make sure this radio button is selected (has a dot in it). If not, click it to select it.
At this point you could use the Browse button to find the folder into which you want to extract these files. For our purposes, we don't need to do that. We are going to keep this simple and just extract the files into the "gfinst" folder you have already created. To do that, just replace whatever is in the dialog box next to the Disk radio button with a single dot ("."). See the example below.

The single dot, ".", means "use the current folder." The "current" folder is the folder you entered in order to open this ZIP file - "gfinst".
- Click on the Extract button.
- The files inside of GFace12.zip will be extracted into the "gfinst" folder. You should see the Extract / Test Zip window, like this:

- Click on the Done button.
- Close the PKzip for Windows window by clicking on File and then Exit.
- The Please Register! window appears. Click on the OK button to finish your PKzip for Windows session.
- Congratulations, you have unzipped your first ZIP file!
E. Installing and Starting GreenFace
While it is technically not part of this tutorial, in fairness I should tell you how to install and start the GreenFace game. You did, after all, go to the trouble of downloading it!
- Look at the icons on the Windows desktop. Look for the "gfinst" folder you created in section C. See it? Good. Double click it to open it.
- One of the files you extracted into this folder is called "Setup.exe". See it? Good. Double click it to install GreenFace onto your computer.
- The Setup window appears, click on the Yes button.
- Follow the prompts to complete the installation. Leave everything at the default settings until you get to the Setup Completed window. When you reach this window, click on the check box labeled "Yes, I would like to view the README file" to uncheck the box.
- Click on the Finish button.
- Again, go back to the Windows desktop and look at the icons. A new one has been added. It is named "GreenFace". Here is what it looks like:

- Double click the GreenFace icon to start the GreenFace game.
- On the "AMISOFT" logo screen, click your mouse or just wait to clear the logo.
- Click on Start Game. (If you want to read the instructions first, click on Information, instead. How old fashioned, reading the instructions before you jump right in!)
- Follow the prompts to start and play the game!
- To quit the game, just hit the "Esc" key.
- Hit the "Esc" key again.
- Click on Exit.
- Hit the "Esc" key again to leave the "beg" screen.
- Enjoy!
Knowing how to create a ZIP file is a skill that comes in handy. For example, when you need to e-mail several large files to a friend or need to backup large files to a floppy disk (or disks), making a ZIP file is often the best solution.
Here is a tutorial that shows you the basics of making a ZIP file using PKzip for Windows. For tasks that are more advanced, see part V of this tutorial. You may also wish to consult the PKzip for Windows on-line documentation. To do that, just click on Help and then Index from PKzip for Windows.
- Click on Start.
- Click on Programs.
- Click on PKware.
- Click on PKzip for Windows. The PKzip for Windows window will open.
- Click on File.
- Click on New.
- Click on .ZIP File.... The Save As window opens. Are you in the "My Documents" folder? If so, skip to step 13. If not, continue with the next step.
- Click on the Up One Level button. This button will take you up the folder "tree." The button looks like this:

- Here is what the window looks like as you click on the Up One Level button:

- Keep clicking the Up One Level button until it "grays out."
- You should now be at the "Desktop" level - the top level in your folder tree. You should see a folder called "My Documents". The Save As window should now look something like this:

- Double click the "My Documents" folder to open it. Here is what my Save As window looks like after I have opened the "My Documents" folder:

- In the File name: dialog box, type in "test.zip" (without the quotes) and click on the Save button.
- The Add Files window will open up. This is where you will compress files and add them to your new ZIP file. Don't worry, the original files will not be altered by this process, only *copies* of the files will be added to the ZIP file. This is what the Add Files window looks like:

- I chose the "My Documents" folder for this tutorial because many popular word processing programs will store the user's word processor files in the "My Documents" folder. Word processor files are highly compressible and make excellent candidates for a ZIP file. In my "My Documents" folder, I have several Microsoft Word format files (".doc" files) and several WordPerfect format files (".wpd" files). These are both word processor file types. In this example, I will compress some of these files into a new ZIP file called "test.zip". You will, of course, not have the same files in your "My Documents" folder as I have in mine. As you go through the following steps, just substitute your own files for the ones in this example.
- To select some files, hold down the Ctrl key and click on the desired files in the list. You may have to scroll down the list to find all the files that you wish to zip. Release the Ctrl key.
- Click on the Add Files button. The selected files will now appear in the Files & Directories To ZIP dialog box.
- To create your ZIP file, just click on the OK button.

- The Add Status window will pop up. You will see each file compress with the final amount of compression displayed as a percentage. The higher the percentage, the better the compression. Click on the Done button to finish creating the ZIP file.

- PKzip for Windows will now open the new "test.zip" file and will show you its contents. You can look at the sizes of the original files and compare them to their sizes as compressed. Here is a snapshot of a portion of that window:

- When you are done looking at the innards of "test.zip", click on File and then Exit to shutdown PKzip for Windows.
- The Please Register! window appears. Click on the OK button to finish your PKzip for Windows session.
- OK, let us go find that ZIP file you just created! *RIGHT* click on the Start button.
- Click on Explore.
- Find the "My Documents" folder in the "Folders" list (scroll up and down if needed). Double click it to open it.
- Click on View and then on Details to display the files in a list with complete information about each file.
- Scroll down the list of files until you find "test.zip". There it is! You can now e-mail this file to a friend, copy it to a floppy, burn it to a CD, etc. If you want to open this file with PKzip for Windows, just double click it.
- Congratulations, you have created your first ZIP file! Click on the Close button in the upper right hand corner of the Windows Explorer to exit the Windows Explorer window. The close button looks like this:
This portion of the tutorial shows you some useful options you can take advantage of when you create a ZIP file. If you are using the tutorial in printed form, keep part IV handy as we will be referring to various steps in that part as we go along.
A. Creating ZIP Files that "Span" Multiple Disks
Are you copying your ZIP files to standard floppy disks, high capacity floppy disks, removable memory cards, or some other form of removable media? If so, you will eventually run into the problem that your ZIP file is too big to fit onto one disk. To get around this, PKzip can actually copy the ZIP file onto multiple disks. This is known as "spaning" disks. As PKzip fills each disk with data, it prompts you to insert an additional disk. This continues until the ZIP file is completely copied.
Using PKzip to span disks is easy. PKzip automatically knows which drives on your system are removable media. If you tell PKzip to create a new ZIP file on one of these drives, PKzip will automatically span disks and will prompt you to "feed" disks into the drive until the ZIP file is complete.
To create a ZIP file that "spans" disks, return to step 13 from part IV. In this step we just typed the name of the ZIP file we wanted to create, "test.zip," into the dialog box. To create a ZIP file that spans multiple disks, add the drive letter of your removable media drive, a colon, and a "slash" to the filename. For example, to create a ZIP file that spans multiple floppy disks inserted into the "A" floppy drive, you would write the filename like this:
a:\test.zip
PKzip for Windows will compress the file and then will begin copying it to the first disk. When the first disk is full, PKzip for Windows will prompt you to remove the existing disk and insert another, blank, formatted disk. This process will continue until the ZIP file has been completely copied to floppy disks. Make sure you have enough blank, formatted floppy disks (or whatever removable media you are using) on hand to accommodate the big ZIP file.
(Tip: To figure out how many disks you will need, you may wish to create a normal, non-spanned ZIP file on your hard drive first. Look at the file size of that file and then divide the size of that file by the capacity of your media. For example, if the size of the non-spanned ZIP file is 11 megabytes and you want to copy it to 1.44 megabyte floppy disks, you will need 8 blank, formatted floppy disks on hand when you begin to create the spanned ZIP file.)
B. Creating Self-Extracting ZIP Files
C. Creating Password-Protected ZIP Files
D. Setting the Compression Level
Tutorials for PKzip version 2.04g for DOS These tutorials were the first ones I wrote and were designed for users of MS-DOS and Windows 3.x. These tutorials explained how to zip and unzip ZIP files with PKzip 2.04g for DOS. Because MS-DOS and the Windows 3.x operating systems are not widely used anymore, PKzip 2.04g for DOS is not widely used anymore. To keep up with the times, I wrote new tutorials for this web site that focus on the Windows version of PKzip. This current version of the web site is the result of my efforts.
Just in case you should need it, however, I have archived the old DOS-oriented tutorials at this web site:
http://www.eurekais.com/brock/zipold/aazip.htm
Just click on the link above to view the old tutorials.
This web page is Copyright © 1996-2001 by Brock Wood, all rights reserved.
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