Understanding EPUB vs PDF
EPUB (Electronic Publication) is designed to be "reflowable." This means the text adapts to screen size, much like a web page. It's great for reading on small Kindles or phones but terrible for printing or referencing specific locations.
PDF (Portable Document Format) is "fixed-layout." It creates a digital paper where every word and image has a permanent X,Y coordinate. Converting EPUB to PDF essentially lays out your book onto virtual paper.
