Dashboard component source reports
Key Takeaway
Dashboards hold no data of their own: each widget pulls its data from exactly one source report.
A source report is the report that supplies the data for a dashboard widget, such as a chart, gauge, metric or table. Knowing how source reports work explains what a dashboard can show, who sees what data, how dashboard filters behave and why some dashboards are slow.
Widgets and their source reports
Reports provide all the data shown in a dashboard. Each widget has exactly one source report. Different widgets can use different source reports, so one dashboard can show data from many reports. Several widgets can also share the same source report.
In Salesforce Classic, widgets are called components.