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How to Unzip and Zip files

zipped file icon Introduction | Unzipping Files | Zipping Files

Our website has many large files available in zipped or compressed format. The result is a smaller file that downloads faster. If you haven't used zipped files before, or are having trouble working with them, this tutorial is to help you.

- What is a zipped (or compressed) file (or folder)?

Zipped file
Compressed file
Zipped folder
Compressed folder
Zipped archive

Zipped files (known by many names, see the table to the right, but in this document called "zipped files") are one or more files on a computer disk that have been combined into a single file in a space-efficient manner to reduce their total file size. This is very useful when disk space is limited or when people download files. Since multiple files can be stored in a zipped file, a single file can be downloaded then unzipped to easily download many files at once. You can think of a zipped file as a set of books on a shelf:

[books on a shelf]
Photo Credit: Flickr user callumscott2.

The set of books is arranged so that they take a very small amount of space, but you can't use or read them while arranged in this compressed manner.

Unzipping files

In order to work with zipped files, they must be unzipped or extracted first. Windows has a built in program called Windows Compressed Folders which can do this for you. If you have installed a zip program, such as WinZip* or 7-Zip*, Windows Compressed Folders may not be easily available on your computer. If you follow the instructions below for Windows Compressed Folders, but a different program opens, you can still follow the instructions listed, and it should generally still work.

- Unzipping a file with Windows Compressed Folders

  1. ↓ TIP: Check the box for each step you complete, keeping the next step clear.
  1. This tutorial assumes you can see file extensions, which unfortunately is not the default for Windows installations. To show these file extensions, see Microsoft's documentation for Vista or XP. If you don't or can't show file extensions, you can still use the file icon to determine file type.
  2. Find the zipped file that you want to unzip in Windows Explorer. In this example, I'm showing cvs-eep-entrytool-v2.2.7.zip, in the folder C:\data. Windows XP is shown here, but Windows Vista works in the same way:

    Note that the file extension is .zip for zipped file.
  3. Next, double-click the zipped file. This opens up the zipped file so that you can see the files that are inside it. With the above analogy of a set of books on a bookshelf, you are now seeing the book spines on the shelf:

    Notice the address bar now says that you are in a folder with a .zip extension and shows a zipped file icon as well. The file inside this zipped file is shown as a normal unzipped file. In this case, it's an .mdb file or Microsoft database. Do not double-click this file to open it when inside a zipped folder. That's like trying to read a book before taking it off the shelf.

    This step is the step that confuses a lot of people. This appears to be a normal folder on your computer, but in fact, you are within a single zipped file.
  4. Single-click the file(s) and/or folder(s) you want to unzip. If you want to select all files and folders (even if there is only one) in the .zip file, press Ctrl-A on your keyboard:

    Notice that the files are now selected. In the above screenshot, a blue background shows that a file is selected. The background for selected files could be a different color on your computer.
  5. Now, copy the file(s) by pressing Ctrl-C on your keyboard.
  6. Then, click the "back" button to return to the previous folder:
  7. Now you are in the original folder, which is not a zipped file (in this case, C:\data):
  8. Lastly, paste the file(s) into this folder by pressing Ctrl-V on your keyboard. This copies the files as unzipped files into the folder you are currently viewing:

    This may take a few minutes or longer for large files.
  9. When the file has completed copying, both the .zip file and the unzipped file(s) are in the same folder. You can use the .zip file as a backup copy or delete it. You can now work with the unzipped files. In the above analogy, you have pulled book(s) off the shelf and can read them. Enjoy!

- Unzipping a file with other zip programs

Other software programs exist for zipping and unzipping files. Two popular programs are WinZip * and 7-Zip *. Both of these allow you to unzip and zip with two clicks:

Here, I have right-clicked on the zipped file and selected "Extract to here." "Extract" is the same thing as "unzip." Windows also sometimes places "Extract files" links in toolbars which may be useful to you. Windows generally opens a wizard to ask where you want the files extracted. The location of the "extract files" tool varies depending on how Windows Explorer is set up and what version of Windows you are using.

- Zipping a file with Windows Compressed Folders

  1. ↓ TIP: Check the box for each step you complete, keeping the next step clear.
  1. To zip a file, find the file in Windows Explorer.
  2. Right-click on the file, left-click on Send To > , then left-click on Compressed (Zipped) Folder:
  3. Windows creates a temporary file (highlighted letters) and may show a "Compressing..." progress box:
  4. When Windows finishes compression, a new .zip file has been created in the same folder as your unzipped file, with the same name except with a .zip extension:

    Note that in most cases, the file size will be much smaller. Some files can't be compressed much, such as .jpg pictures. Others files, such as text and database files, compress to a small fraction of the size of the uncompressed file.

- Zipping with other programs

As above, other programs exist to zip files with two clicks:

*This page is informational only and is not an endorsement of any particular software.