Why an e-book page is not really a page
Many e-books store a book’s words and structure separately from the exact shape of each page. The file marks elements such as paragraphs, headings, and emphasis; the reading app decides how to display them. When a reader changes the font size, the app recalculates how many words fit across a line and how many lines fit on the screen. A paragraph may therefore begin or end in a different place, and page numbers—if the app shows them—can change too.
The reader’s screen becomes part of the layout
That flexibility depends on the device’s available space. A phone held upright has a narrower reading area than a tablet held sideways. The app also accounts for settings such as margins, line spacing, and typeface. In effect, the same text is continually typeset to fit the reader’s chosen conditions, rather than preserved as a fixed arrangement.
This is useful beyond comfort. Larger type can make a book easier to read for someone with low vision, while the underlying words remain unchanged. The tradeoff is that readers cannot rely on a particular phrase appearing on a particular screen or at a fixed page number; references to a location may need to use chapter or section markers instead.
Reflow is a design choice, not a universal rule
A fixed-layout file, such as one designed to preserve a picture book’s illustrations or a comic’s panel arrangement, prioritizes visual placement over adjustable text. A reflowable novel makes the opposite choice: it gives up a single, stable page design so the words can adapt to the reader. That is why a digital book can feel less like a stack of pages and more like text being set anew each time it is opened.
