DocX is a new file format created by Microsoft for the newest version of Word (2007). The "X" in the file extension signifies support for the XML standard, which was also developed by Microsoft. DocX files can currently only be created in a limited number of ways, though they are backward compatible for viewing in earlier versions of Word by using a compatibility pack created by Microsoft. The addition of the "X" extension applies to other products in the Microsoft 2007 Office suite as well.
Download and install any trial version of Microsoft Office 2007 (see Resources). This will allow you to create docX files for the length of the trial period, which runs for 30 days. After that, you will be able to use the software to view docX files, but you will no longer be able to save the files to that format.
Purchase Microsoft Office 2007. Once you have purchased the software, you can create docX files as often as you like, as well as files created with the new extension for Excel and Powerpoint, which feature the same "X" addition to the file extension.
Use the Microsoft 2007 online try-before-you-buy to test drive Word and other Office products online without having to install (see Resources). You can create and save docX files during the test drive in the same way as you create docX files in the downloaded version of the software.
Go to the "Start" button and create a new document. Once you have written the document, save the file. Word 2007 automatically saves as its new native file format of docX, which is similar to the old .doc extension except that it now includes Microsoft XML support.
You can view, but not edit, docX files with the free Word viewer available from Microsoft.