I was thinking of the word leaf and how it is not often used in relation to books and metaphors that we use in screen-media.
The page of a book is the surface on which words and pictures are presented. The leaf refers to the actual sheet. A leaf will have two pages - one on each side. We say in the English idiom:
Turn a new leaf
To mean, starting again in a positive way. Of course, this means turning two pages. Screens are only one sided but there are a variety of ebook systems that simulate the turning of a page. I wrote an article about this a while ago, so I make a link to it here.