If you have a book handy, open it toward the front, and what do you find? You probably came across a title or copyright page. You may have even had the fortune of finding a table of contents. Many times, we pay these sorts of things no mind. We're used to seeing them all the time in just about every book we've encountered, so we tend to take them for granted. A few centuries ago, however, text features, or elements existing independently of a main text and intended to enhance readers' experiences with the text, would have been much appreciated.
Given a scroll's general unwieldiness, our ancient predecessors found it difficult to navigate efficiently from one part of a text to another, so text features would have been of relatively little use to them beyond a simple title. However, from around the first century A.D., people have been binding pages of various materials together (i.e. papyrus, parchment, paper) to form what we would refer to as the 'book.'
Like road markers or mall directories, directional text features are intended to help direct readers to specific locations in a text. These elements could be as simple as a table of contents, chapter headings, or page numbers, but other directional text features might be more involved.