If you are opening a file, your computer may not have the correct software to view it (yet). To help a computer to know how to open a file each one is given a “file extension”. While the file extension is usually hidden, it is placed at the end of a file name as period (.) followed by a few letters (usually 3).
While the software to create these files usually comes at a cost, the ability to read them typically does not. Below are a list of common file extensions and links to free utilities which should enable you to view them. As always, please read the license agreement before installing any software.
PDF (portable document format):
Adobe Acrobat Reader
Foxit PDF Reader
DOC, DOCX (Microsoft Word document)
XLS, XLSX (Microsoft Excel spreadsheet)
PPT, PPTX (Microsoft PowerPoint presentation)
PowerPoint Viewer 2007
Microsoft Office Compatibility Pack