We probably all recognise the most common file extensions (.doc, .ppt, jpeg, etc) but there are thousands of different extensions around.
Try using Wolfram | Alpha. Put in the extension, with the full stop, and it will tell you what the full name is, the type and supporting applications.
Alternatively point your browser to: http://pc.net/extensions/ or www.file-extensions.org/
Phil Bradley in CILIP's Information Update.
