Since 2007, Microsoft began to use a file format docx, which is created by using the Office Open XML. The format is a zip-file containing the text in the form of XML, graphics and other data that can be translated into a sequence of bits using patent-protected binary formats. At first it was assumed that this format will replace the doc, but both formats are still used today.
The extension allows you to save audiovisual and textual information as a presentation or a slide show. Is used solely for viewing the created presentation and has no editing capabilities. It’s based on the XML format and can be opened with PowerPoint 2007 and newer versions. The file may be viewed by the users who do not own a commercial PC version of MS PowerPoint but who could still view the presentation using PowerPoint Viewer.