This is the most popular file type for presentations. It has an open equivalence, the odp format, which is the default format of LibreOffice.
Name : Abreviation of PowerPoint
Mime : application/vnd.ms-powerpoint
Licence : Proprietary
Type : Document Diaporama
Free softwares to open pps : LibreOffice Impress
Non free softwares to open pps : Microsoft Powerpoint