If you have an SSRS report deployed to a Report Server you can use URL parameters to link to it in such a way that the parameters pane is collapsed by default. This can be helpful especially when your clients aren't likely to use it very frequently and if it takes up a lot of space on the screen.
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All you have to do is add on the following to the end of your report URL:
?rc:Parameters=Collapsed
So it will look something like this:
https://server/reports/report/FolderName/ReportName?rc:Parameters=Collapsed
It's that easy!