Rotate PDF.

The angle is added to the source page’s existing rotation. Use the preview to confirm that the text is upright instead of assuming a 90° setting always means the same visual result.

The 0° choice leaves the source orientation unchanged. It does not remove a rotation already stored in the original PDF.

Apply to all pages starts enabled and suits a consistently sideways packet. Turn it off when only a few pages need correction.

Use the page-range controls for groups such as odd or even positions when appropriate. A mixed document often needs more than one orientation choice.

Existing text, vector drawing detail and source image pixels are not converted into a new screenshot just to turn the page. This makes quarter-turn rotation a useful first step for digital PDFs.

Review the exported file when annotations or forms are important, and keep the original as with any document edit.

Use Rotate PDF for sideways or upside-down pages. Use Deskew PDF when text lines slope by a few degrees within an otherwise correctly oriented page.

Deskew has a different output tradeoff: it rebuilds page images. Make the simplest change that solves the actual orientation problem.