Why rotation is a stored property, not a re-drawn page#
A PDF page carries its own rotation as a stored number — 0, 90, 180, or 270 — that a PDF viewer reads and applies when displaying the page; the actual page content underneath never moves. Rotating a page here means changing that stored number, not redrawing the page sideways, which is why rotation is instant and lossless regardless of how complex the page content is.
Why rotating twice gives you 180°, not a reset#
Because rotation is stored per page as an existing value, this tool adds the requested rotation to whatever a page is already set to (wrapping back to 0 past 360), rather than overwriting it. Rotate a page 90° once, then rotate it 90° again, and it ends up at 180° — matching what someone would actually expect from clicking a "rotate" button twice, rather than each click starting over from the page's original orientation.
Rotating a selection versus rotating everything#
A scanned document sometimes has just one or two pages that came in sideways while the rest are already correct — rotating the whole file would fix the bad pages and break the good ones. Leaving the page field blank (or typing "all") rotates every page; listing specific pages or ranges rotates only those, leaving everything else exactly as it was.