Blender 3D: HotKeys/Key/PeriodKey

The Period Key

• .KEY (on the alphanumeric pad) - changes the pivot point to the 3D cursor. The pivot point is the point where all things meet when scaled to 0, and the point of 0 translation during a rotation transformation. See the menu on the 3D view header, located immediately to the right of the Viewport Shading menu.
• CTRL+.KEY - changes the pivot point to individual origins.
• ALT+.KEY - changes the pivot point to active element.