A common technique virus authors use is disguising a .exe file as .avi , .jpg, .doc, or .txt when it’s actually a executable file (.exe) making you run and install a malicious program.
For example a bad guy can name a malware “must-see-video.avi.exe”, if your file extension was hidden you would not realize the file was a .exe because you would only see “must-see-video.avi” and once you realized what you did it’s to late.
How Show File Extensions in Windows XP, Vista, 7
Show file extensions in Windows XP:
- Go to My Computer (WINKEY+E.)
- Click Tools
- Select Folder Options.

- Click the View tab, uncheck Hide extensions for known file types, and click OK.

Show File Extensions in Windows Vista/7 :
- Go to Computer (WINKEY+E.)
- Press the ALT key to show the action toolbar.
- Click Tools
- Select Folder Options.

- Click the View tab, uncheck Hide extensions for known file types, and click OK.


