A sample Office Open XML Format ZIP package.
After you save a copy of your file with the .zip extension, you can open the ZIP package in Windows Explorer to view its contents, just as you would open any compressed (zipped) folder.
When you open any Office Open XML ZIP package, you see a _rels folder and the file [Content_Types].xml, which we'll discuss later. Most Office Open XML file types also contain the docProps folder, which stores file properties.
The word folder shown here indicates that this is a Word 2007 file. In place of this folder, an Excel 2007 ZIP package contains a folder named xl, and a PowerPoint 2007 ZIP package contains a folder named ppt.
Note Although you can view the contents of an Office Open XML ZIP package with any software designed for viewing files that use ZIP compression technology, some of these tools will not show the folder structure, which is an essential part of managing your Office Open XML ZIP package. When you open the ZIP package in Windows Explorer, the folder structure is always visible.