.KEYNOTE File Extension

The keynote file extension is associated with Apple Keynote, a presentation software application developed as a part of the iWork productivity suite (which also includes Pages and Numbers applications) by Apple Inc.

The Keynote Presentation is XML based and may contain basic text documents or elaborated multi-page brochures, including images, special texts, tables, graphs, charts and more. be created from a blank page or based on saved template.

The keynote file is basically a folder named as document_name.keynote that  main presentation document, previews and some metadata. This file format was used in earlier versions of Keynote up to Keynote '06.

The latest versions of iWork Keynote use the key file extension instead. Keynote '09 is also able to save files in keynote format, but you have to change the presentation preferences for that. 

.KEYNOTE file format is deprecated and this file format is no longer supported.

Currently, .KEYNOTE file type is not actively used and is obsolete. This usually happens with system files in older operating systems, files from long-discontinued software, or with previous versions of some file types (documents, projects, images, etc.) that were replaced in later versions of the original programs.

How to open:

Use Keynote application from Apple's iWork office suite to open *.keynote files.However, latest Keynote has sometimes problem with opening older *.keynote presentations.

How to convert:

Normally KEYNOTE file format cannot be converted to other presentation formats with all its features. However, Keynote offers the possibility of exporting the presentation to MOV movies, and to PowerPoint PPS format, albeit at the cost of quality.