Refresh Button in Report View

Hi all,

I am exploring the online environment of Power BI. I do know the different options and buttons available, however one remains a secret.

While in the Report View, there is a button "Refresh". However, I could not find documentation anywhere what it actually refreshes. Is it the data in the online environment, a sync with the "offline" dataset or a referesh of the tiles?

I did found an answer in this thread, but unfortunately I still don't understand the use of the button. (http://community.powerbi.com/t5/Service/Refresh-button-in-report-tab/m-p/13177/highlight/true#M4706)

Cheers