Why pages end up sideways
Scanners, phone scanning apps and some printers save pages in the wrong direction, especially landscape tables and pages fed upside down. Sideways pages are hard to read on screen and print badly. Rotating fixes the direction permanently in the file.
What happens when you rotate
Choose 90° clockwise, 180° or 90° anticlockwise, and either all pages or only the pages you type, such as 2, 5-7. Rotation only changes how each page is displayed: the text, pictures, links and quality stay exactly the same, and the text remains selectable.
Choosing the right direction
If the top of the page points to the left, rotate 90° clockwise. If it points to the right, rotate 90° anticlockwise. If the page is upside down, rotate 180°. When only a few pages are wrong, type their numbers so the correct pages are not turned.
Common problems and how to fix them
The page is still sideways: rotate again in the other direction — two 90° turns equal 180°. Some tools say a page must be at 0°: tools such as Add PDF Links, Annotate PDF and Create Fillable PDF Forms need unrotated pages, so rotate before using them. The PDF needs a password: unlock it first.
Good habits
Check every page in the preview after rotating, fix rotation before merging or adding page numbers, and keep the original scan.