Use Microsoft Office to Edit Documents Saved in Google Drive

As of today, Google has introduced a plugin for Microsoft Office allowing users to use Word, Excel, and PowerPoint to open their Office files stored in Drive. Previously, Google Docs allowed users to save Office Documents (as well as most other file formats) to Drive, but editing required users to convert the document to Google Drive format, which sometimes led to confusion and multiple versions of the same document.

• You may save files in Office directly to Google Drive by selecting File > Save As and selecting Google Drive as the destination.
• Using Microsoft Office to edit Office documents shared with you through Google Drive is now quicker and easier.
• Users who prefer Google Drive 

Google Docs opened using the Microsoft Office interface will still open in your browser, but should you want to add Office features to your Google Docs, you can download as a Microsoft Office document, open in an Office program. Microsoft Office integration does not yet extend to Office for Mac, nor is it a part of Office Online (which allows storage to Dropbox and Microsoft OneDrive), but the Microsoft Office desktop plugin should be a must-have for Office devotees.
Further Reading:

• Google Drive Blog: Introducing the Google Drive plug-in for Microsoft Office
• 5 Apps That Help Microsoft Office and Google Apps Play Nice Together