When you create a new part or assembly, the three default planes are aligned with specific views. The plane you select for your first sketch determines the orientation of your part.
For example, if you choose *Front in the Orientation dialog box (or add a front view to a drawing), the view is normal to the Front Plane.
If you open a new part and select a sketch tool, you are prompted to select a plane.
If your first sketch is a top view, select the Top Plane.
If your first sketch is a left or right view, select the Right Plane.
You do not have to use one of the default planes for your first sketch; you can create a new plane at any angle. The orientation of views is still determined by the default planes, however.
You can reorient the part (to change Front to Top for example) with Update Standard Views 
in the Orientation dialog box.