When you create a new page, no .aspx files are created. All pages in the menu are served from /Default.aspx?pageid=x where x is the page id of the page. But we use url re-writing to have friendly urls. So a record is created in the database that maps /SomePageName.aspx to /Default.aspx?pageid=x
So all content other than uploaded images is stored in the database, though there are of course physical .aspx pages used for administration and editing.
Hope it helps,