Mirror every page horizontally or vertically
Rotating turns a page around its centre — text stays readable, just sideways or upside down. Flipping mirrors it, so text reads backwards. Flip is for genuine mirror-image originals, like a scan made through the back of a page or a reversed transparency; rotate is for pages that are simply turned the wrong way.
Horizontal mirrors left-to-right (the most common fix for back-to-front scans). Vertical mirrors top-to-bottom. If your text reads backwards left-to-right, choose horizontal.
No. The mirror is applied as a coordinate transform, so text and vector graphics stay razor sharp — nothing is rasterized or re-encoded.
Flipping rebuilds the page geometry, so document bookmarks, form fields and comments are not carried across — a field pinned to the un-mirrored layout would end up in the wrong place. The page content itself is fully preserved.