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.
Designed to let users easily create, play and share presentations, Keynote contains most of the features found in modern presentation software, such as a slide navigator, the ability to add tables, shapes and charts to slides and a powerful media browser which allows users to drag and drop music from from iTunes, and photos from iPhoto and Aperture into their slides.
Keynote contains a large number of pre-designed themes to let users select common presentation formats, and powerful graphics tools to manipulate embedded images and provide advanced 3D transitions between slides (powered by OpenGL). The major Keynote releases are summarised below:
First version - basic features - Import Powerpoint presentations, slide navigator, graphics support for rotations, resizing and opacity, charts and slide transitions.
Released in iWork '05. Contained improved animations for slides and text, iLife media browser, new themes, more presenter controls, embedded hyperlinks and the ability to export presentations to Macromedia Flash.
Released in iWork '06 with new themes, HD-capability, improved graphing and table features, cinematic transitions and 3D graphs.
Released in iWork '08 with easier to use animation features, new templates, smart builds (for predefined animations), instant alpha (for removing backgrounds from photographs), and a new narration to add a voiceover to slideshows.
Released in iWork '09. Contains support for MathType equations, a new share menu, trackpad support, "magic move" (for easier transitions), improved presenter tools, but removed support for exporting to Flash.
Added support for Mac OS X Lion, and included support for full screen functionality, auto-save, resume and versioning. Also with improved compatibility with Microsoft Office.
Support added for iCloud documents and Retina displays.
Adds Keynote support for iOS 6.0
Part of new iWork suite for Mac, with 64-bit support and iCloud syncing.
Improved compatibility with Microsoft Powerpoint.
Updated design of OS X Yosemite, iOS 8 and a new file format to improve support for 3rd party online services.
A .key file is actually a compressed ZIP file comprised of a number of other different files combined that together make up a .key file. The most recent version of Keynote saves files with an "Index" directory containing Apple's proprietary IWA file format, a "Metadata" directory with .plist files, a "Data" directory with image assets (e.g. backgrounds and photos used in slides) and one or more jpg files for allowing quick previews.
Files created by Keynote in iWork cannot be opened by programs other than iWork.