PPSX is a PowerPoint Open XML Slide Show - it is primarily designed to be non-editable and to simply playback the Powerpoint presentation. It differs from PPTX which allows for the file to be editable. The 'X' extension refers to Microsoft Office 2007, 2010 and 2012 which ZIP compress the file and is therefore different from the previous versions which were generally have larger file sizes.
PPSX are compressed and based on the ECMA-376 standard for Office Open XML. It supports Text, Images, Audio and Video and is stored in a zipped directory format which matches the OPC structure. Just like the PPTX format the PPSX format improves file sizing, data recovery and data management and allows for other applications to interact with it due to the XML structure.
Originally developed by Forethought, who Microsoft bought out, PPT is the worlds most popular presentation file format. It is a very powerful tool that you can use to create presentations that include pictures, graphs, text and many other objects. Many businesses and students that have to present something will almost always do their presentation using Microsoft PowerPoint.
A large part of any presentation is how the text enters, appears and exits the screen. Entrance, emphasis, and exit of elements on a slide itself are controlled by what PowerPoint calls Custom Animations Transitions. These can be animated in a variety of ways. For example you can customise the animation to create small story boards by animating pictures to enter, exit or move. With different type of callouts, speech bubbles with edited text can be sent on and off to create speech. The overall design of a presentation can dictate how all the other slides appear and operate, this is called a master slide. Everything from design to the text on the slide can be edited using a primitive outliner.