At its core, an EPUB file is essentially a miniature website packaged into a single compressed folder. According to Wikipedia , it utilizes established web standards like and CSS to structure and style text. This architecture allows the content to be "reflowable"—meaning the text automatically adjusts to fit the screen size, whether it is being read on a smartphone, tablet, or dedicated e-reader. This is a significant departure from fixed-layout formats like PDF, which require cumbersome zooming and horizontal scrolling on smaller screens. Accessibility and Versatility

For centuries, the printed page was the immutable standard for literature. However, the rise of the digital age demanded a more flexible container for information. The EPUB format , developed by the International Digital Publishing Forum (IDPF), emerged as the definitive open standard that bridged the gap between traditional typesetting and modern, multi-device accessibility. The Technical Foundation

One of the most transformative aspects of EPUB is its commitment to accessibility. Because the format is built on web standards, it inherently supports features that aid readers with visual impairments. As noted by experts at the DAISY Consortium, EPUB allows users to easily increase font sizes, change contrast, or use text-to-speech tools without breaking the book's structure.

The Evolution of Digital Reading: The Impact of the EPUB Format