Once you have a report built, you will want to be able to consume it on a regular basis to take advantage of the most recent data. If you have created a report and simply saved it, you will run into a message in the Viewer like this:

To publish the the report, go back to the Editor and click the 'Publish' button. This will publish the most recent version of this View for anyone with access to it.

If you ever want to make changes to this report, your changes will be saved as a draft every time you click 'SAVE' and won't be reflected to end users viewing it until you click 'PUBLISH'.