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How Windows Manages Files- Extensions II
On the previous page, we were introduced to file extensions and their function. Here is a table of some of the common extensions that you will encounter. Also listed is a brief description of what type of file each extension is for.

Some Examples of Extensions

This table lists a few of the most common file extensions and a little information about them.
Extension Description Comments
jpg, png, gif Graphics, pictures Opened by default browser or by graphics program
bmp (Bulky) graphics Opened by Paint or by graphics program
doc, docx Word processing file Opened by or Microsoft Word or alternative office software
xls, xlsx Spreadsheet Opened by or Microsoft Excel or alternative spreadsheet software
ppt, pptx Powerpoint slideshow Opened by or Microsoft Powerpoint or alternative software
txt Text file Opened by Notepad or text editor or Word, etc .
pdf Portable document file Opened by default browser or PDF software
htm, html Web pages, etc. Viewed in browser, code edited in text editor or
wav Audio file Opened by Windows Media Player or multimedia software
mp3 Audio file Opened by Windows Media Player or multimedia software
avi Video clip Opened by Windows Media Player or multimedia software
wmv Windows media video Opened by Windows Media Player or multimedia software
rm, mp4, mpg Video clip Opened by multimedia software
mov, qt Apple Quicktime video Opened by Quicktime or multimedia software
swf Adobe Flash video Opened by browser or Adobe Flash player
dll Dynamic link library Used by software in a variety of functions. Should be left alone.
exe Executable file File that actually runs software (also type of ZIP)
zip Compressed file Opened by native Windows function or archive software such as 7Zip
msi Installer program Used to install Windows programs
reg Windows Registry file Used to modify the Windows Registry
bat, cmd Batch file Executable script
vbs Visual basic script Executable script
js Javascript file Executable script opened by browser
jar Java Archive File Executable file opened by browser plug-in or Java player
iso Container file for contents of optical disk Mounted natively in Windows 8. Otherwise opened by disk creation software or certain archive programs

There are thousands of extensions, however. Among the sites with large lists and descriptions of the different file types are:

Doing a search in Google or other search engine will turn up many others.

Next: What happens when Windows does not recognize an extension