Understanding the New PowerPoint XML Format

Not that you particularly need to know it if you do not share presentations with others, but PowerPoint 2007 presentations are formatted using XML (Extensible Markup Language), not the binary file format of previous PowerPoint versions. A markup language is a computer language, or set of codes, that determines how text, graphics, colors, and all else is displayed on a computer screen. You may have heard of HTML (Hypertext Markup Language). HTML is the markup language that Web browsers read to display Web pages on computer screens.

Microsoft adopted XML for PowerPoint 2007 and its other Office programs (except Publisher) to make sharing information between the programs easier. Because files made in the Office 2007 programs are formatted in XML - because they are written in the same language - data from one Office program can be copied to another without the data's having to be translated from one binary file format to another. What is more, files in the XML format are half the size of files written in the old binary formats. And because XML is an open format - programmers know the codes with which the XML is written - people outside Microsoft can write programs that produce XML data for use in Office programs. XML makes it easier for different programs to exchange information.

The new XML format matters to PowerPoint 2007 users who intend to give their presentations to people who do not have PowerPoint 2007. It matters as well to users who will show their presentations on computers on which an earlier version of PowerPoint is installed. Because PowerPoint 2007 presentations are formatted in XML, not the binary file format with which PowerPoint 97, 2000, 2002, and 2003 presentations are formatted, earlier versions of PowerPoint cannot open presentations made in PowerPoint 2007. Before you give a presentation you created to someone who uses PowerPoint 97-2003, save it as a PowerPoint 97-2003 file.

You can tell whether a PowerPoint, Excel, or Word file is formatted for a 2007 program or an earlier version of the program by glancing at its file extension. PowerPoint, Excel, and Word files have four-letter, not three-letter file extensions, with x (for XML) being the last letter. Office program file extensions are here: