In the old user interface all reports existed in the Reports-tab. Ribbon contained items for the standard reports, report shortcuts and recently opened reports. All reports (excluding recently opened reports) were also within the report gallery.
In the new user interface reports can be found from Reports-menu. Five standard reports are listed first. User's recently opened reports, report shortcuts and custom designed reports can be seen in the Gallery which opens from the Report menu, too.
Gallery-page shows reports grouped to three sub-categories: recently opened reports, report shortcuts and custom reports. A report can be opened from the list by clicking the name.