Save a presentation in package or single-file format

By default, Keynote saves your presentation as a single file. If your presentation is very large or has a lot of movie or image files, you may want to save it as a package file.

You can change a package file to a single-file format to improve the performance of Keynote. Some web or email services don’t allow you to upload or attach a package file.

See this Apple Support article for more information.