With Office 2007’s new interface and powerful new tools also comes a new file format. Word 2003’s previous file format has been basically unchanged since Word 97. Feature enhancements have necessitated the modification of Word’s binary format over the years, such as when document versioning and floating tables were introduced.
Even so, you can still open most Word 2003 files in Word 97 and the document looks basically the same. Only if you use newer features will you see a difference, and usually that just means reduced functionality rather than lost data and formatting.
Word 2007 and Word 2003 users will continue to see interoperability. However, Word 2007’s new “native” format is radically different—and better—than the old format. Word 2007’s new format boasts a number of improvements over the older format:
Open format— The basic file is ZIP format, an open standard, which serves as a container for .docx and .docm files. Additionally, many (but not all) components are in XML format (eXtensible Markup Language). Microsoft makes the full specifications available free, and they may be used by anyone royalty-free. In time, this should improve and expand interoperability with products from software publishers other than Microsoft.
Compressed— The ZIP format is compressed, resulting in files that are much smaller. Additionally, Word’s “binary” format has been mostly abandoned (some components such as VBA macros are still written in binary ...