The Orbit tool enables you to change the orientation of a model in a 3-dimensional manner. As you drag the cursor, the model rotates around a pivot point, while the view remains fixed. 

 The pivot point is the base point used when rotating a model with the 
Orbit tool. You can specifiy the pivot point in the following ways: 
- Default pivot point 
- When you first open a model, the target point of the current view is used as the pivot point for orbiting the model. 
- Center tool. 
- You can specify a point on the model, using the Center tool, to use as the pivot point for orbiting.