For Orbit mode, choose View > Orbit, or access the same command from a toolbar or from the bottom scrollbar of the 3D window.
Once you enter Orbit mode, press the left button and drag the mouse to turn the model around its centerpoint (axonometry) or target point (perspective).
If you are in Orbit mode, you cannot edit the model. Click ESC to exit Orbit mode and return to editing mode.
While in editing mode (not in Orbit mode), you can temporarily simulate Orbit mode by pressing Shift together with the mouse scrolling button to orbit the model. Release the keys to stop orbiting.
This type of temporary Orbit requires the model to be redrawn and can result in slowed-down navigation.