SQL:report security--default security roles

Browser
May view folders, reports and subscribe to reports.

The BROWSER cannot deploy a report and cannot upload files (resources).
Content Manager
May manage content in the Report Server. This includes folders, reports and resources.
My Reports
May publish reports and linked reports; manage folders, reports and resources in a users My Reports folder.
Publisher
May publish reports and linked reports to the Report Server. What is a resource?
When you upload a file to report server, the file is a resource.
Publisher can create a report by BIDS and deploy it to the REPORT SERVER. However, the publisher cannot RUN or execute the report definition (cannot Start execution from report definition without publishing it to Report Server). And, the publisher can upload a graphics address.jpg. But it cannot view the content.
Report Builder
May view report definitions.
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How to assign the site-wide security?
http://localhost/reports
Site Settings --Security--Configure site-wide security

System Administrator
View and modify system role assignments, system role definitions, system properties, and shared schedules.
System User
View system properties and shared schedules and Execute Report Definitions.

By default, BUILTIN\Administrators is the member of System Administrator role and Content Manager role.