My Subscriptions provides access to view, modify and add subscriptions for reports. When you subscribe to a report, the report will run automatically based on a defined event. There are various delivery methods (e.g., deliver to History List or Email the results). The defined events are usually related to data updates, but may also allow you to Send Now which actually bypasses a permanent subscription and runs the report immediately for the specified delivery method.
Additionally, there is an option to create a run-on-demand Personal View subscription when viewing a report from the Report Output page. This captures the current layout of a report and allows you to save this Personal View to be re-run at any time on demand.
Click here for more information on Subscriptions.