Simply put, .xlsx is a file extension for the open XML spreadsheet used by Microsoft Excel from 2007 onwards. Why the change in format from earlier versions of Excel?

Citing statements of support from more than 300 companies and organizations, Microsoft claimed on Tuesday that interest in its Office Open XML file format continues to grow. Comments backing the ...

The next version of Office will fully support two new file formats, Strict Open XML and Open Document Format 1.2, Microsoft has announced. In a blog post on Monday, Office standards chief Jim ...

The converter provides read-only access to Office Open XML documents created with Office 2007. For the time being, it's Word-only and can convert those files to Rich Text Files (.rtf).

Microsoft’s Macintosh Business Unit released three updates for its Mac Office products. Office 2008, Office 2004 and the Open XML File Format Converter for Mac are all available from the company ...

Microsoft is trumpeting support for its Office Open XML document file format as an international standard from more than 300 companies and organizations on a new "community" Web site set up by the ...