Filename extensions
A filename extension is the ending of a file that helps identify the type of file in operating systems such as Microsoft Windows. In Microsoft Windows, the file extension is a period that is often followed by three characters, but may also be one, two, or four characters long. For example, the filename "myfile.txt" has an extension of ".txt", which is a file extension associated with text files.
A computer file extension is commonly a three character addition that follows the name of a file. A few of the more common file extensions include EXE, DOC or DOCX, XLS, TXT, PDF, and MP3.
File list in explorer with name and file extension
In the above example, the first file shown in Explorer is "regedit.exe", "regedit" is the name of the file, and ".exe" is the file extension that identifies this file as an executable file. The next file "RtlExUpd.dll", which is a DLL file and another example of a file, and finally the last two files are log files. As can be seen in this example, by having file extensions you can quickly identify the type of file and have a better idea of how that file may be opened.
Tip: If you are trying to find a file with a specific file extension, use wildcards.
How to view a computer filename extension
To view the filename extension of a single file for all versions of Windows follow the steps below. If you want Windows to show the file extensions of every file on the computer by default skip to the next section.
Viewing the filename extension of a single file Right-click the file. Click Properties. In the Properties window, similar to what is shown below you should see the "Type of file:" this is the file type and extension. As can be seen in the example below this file is a TXT file with a .txt file extension and in this case opens with the Text Pad program.
Viewing filename extension in Windows Always show file extensions of all files
Users more familiar with computer files and filename extensions may want to view all computer file extensions to help with locating and browsing files. To do this follow the steps below for your version of Windows.
Windows 2000, XP, Vista, 7, and 8 users • Open My Computer • Click Tools and click Folder Options or click View and then Options depending on your version of Windows. • In the Folder Options window click View tab • Uncheck the box that says Hide file extensions for known file types.
Changing a filename extension Tip: Although any file can be renamed, it doesn't mean that, after it has been renamed, it can be opened with any program. For example, you can rename a .BAT to a .EXE, however it will not run because a .EXE file is a compiled file.
ADDITIONAL info about file handling
When I delete a file on my computer, where does it go? When you first delete a file on a computer, it is moved to the computer's Recycle Bin, Trash, or something similar depending on your operating system. When something is sent to the Recycle Bin or Trash the icon changes to indicate it contains files and if needed allows you to recover deleted file. Later, when you empty the Recycle Bin or Trash, the icon changes back to an empty trash can and the files are deleted.
Once the file has been deleted When a computer deletes a file, it is removing the reference to the file. Once the file header is removed, the computer can no longer see the file. The space the file took up is no longer reserved for that file, and any new file can be stored in that location. What does this mean? The file is no longer readable by the computer. However, the file is still on the hard drive, at least until another file is saved in the same location. Because the file is technically there, it may be able to be recovered using data recovery software, designed to rebuild the file header and allow the computer to see the file again. This software only works if no other file or data has been saved over the top of the deleted file.
Making sure a file cannot be recovered Running a utility program that overwrites all deleted files with zeros or other garbage is the only method of making sure files cannot be recovered. This can also be called a zero fill, because of the writing of the zeroes to the hard drive. When the deleted file space is overwritten by zeroes or any other data it is no longer able to be recovered. How to recover missing, lost, or deleted files Computer hard driveBefore reviewing the below recommendations and suggestions, verify that the files have been deleted; in some cases the files may have been moved. You can search the hard drive for the files you believe to be missing by running find or search on the computer. A free program called “Search Everything” is a highly recommended. Recover file from backup If the file has been backed up to floppy disk or other medium it is recommended that the file be restored from that backup if the file cannot be found. Restore from Recycling Bin or Trash If you are running Apple MacOS or Microsoft Windows and the file has been recently deleted it may still be in the Trash or Recycle Bin. If present within this area it can be recovered.
Download free program or purchase a program When a file is deleted (even when removed from the Recycle Bin) the files are marked as deleted, however it is not removed from the hard drive. Assuming no other file has overwritten the deleted file on the hard drive a recovery program can be used to recover deleted files. Below is a list of freeware file recovery programs that can be used freely to recover lost data. Recuva Restoration Disk Drill - for Mac and Windows Undelete Plus FreeUndelete Photorec PC Inspector File Recover *Not compatible with Vista/7 Tip: When running a program such as Restoration in Windows Vista or 7 and prompted to run as administrator, right-click on the executable and choose the option to run as administrator.
Utilize a service from a company that specializes in recovering lost data Utilize the service of a local data recovery company or an out of state data recovery company. One word of caution is that these services can sometimes be very expensive. It is only recommended they be used if the data is extremely important or data cannot be read from hard drive. Below is a listing of a few major data recovery companies.