Once you add a report parameter to a table or chart filter, people who preview the report see it differently depending on your settings.

If the default value is unspecified for the parameter

When the user previews the report, the Report Parameters pane displays, and they must first select a value for the parameter and click View Report before the report will run.

If you specify a default value for the parameter

When the user previews the report, the report runs immediately, filtered by the default value. To change the parameter value, they must click the Parameters button to display the Report Parameters pane.

If you are previewing a parameterized report

You can preview parameterized page reports, end-user-created reports, and section reports with SQL query parameters as well as Report Explorer parameters.

When the user previews a parameterized report, the Report Parameters pane displays, and they must first select a value for the parameter and click View Report before the report will run.

Reference

Chart Filtering

Table Filtering

Filters and Parameters