Most of the time you don't need to be concerned about file extensions on your files. Sometimes though, when you install a new program, that new program thinks it is all important and makes changes to your computer for you. (Don't you hate it when they do that?) Now, when you double-click on a file icon this new program will open instead of the one you are used to. A good example of this is when you install photo editing type of software that comes with a digital camera. The new program may decide for you that you want to run it to modify your photos, instead of the Photoshop program you prefer to use.
File Extensions - the Source for File Extensions Information, has some nifty free tools to help you repair any file extension problems as well as lots of info and tips to keep your computer running in tip-top condition. Here is the description from their site -
Find file extension details here including easy-to-understand descriptions and associated applications. Search by extension, view common and most visited extensions, and click to extension categories including audio and music files, game files, system files and text files.
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