16. A method as recited in claim 15 , further comprising: receiving, after receiving the third semantic zoom out request, a first semantic zoom in request; and displaying, in response to the first semantic zoom in request, the digital book in the first display area, and displaying the multiple additional digital books in the second display area.
17. A method as recited in claim 16 , further comprising: receiving, after receiving the first semantic zoom in request, a second semantic zoom in request; displaying, in response to the second semantic zoom in request, both the first page of the digital book and the context of the first page in the first display area, and both the second page of the digital book and the context of the second page in the second display area; receiving, after receiving the second semantic zoom in request, a third semantic zoom in request; and displaying, in response to the third semantic zoom in request, the first page without the context of the first page in the first display area, and the second page without the context of the second page in the second display area.