The format is part of the new Office Open XML Formats. It's based on the XML (Extensible Markup Language) programming language.
You don't have to understand XML — that's behind the scenes. Just know that the new format means improvements to PowerPoint. Here are its chief benefits:
Safer presentations Presentations containing unwanted code, macros, or controls are easier to identify and block.
Reduced file size Presentations are automatically compressed.
Improved information security Personal and business-sensitive information is easier to remove.
Improved damaged-file recovery A file can still be opened even if part of it is damaged.
Easier integration Presentation content can be shared with and opened in other programs.