FileCarpenter guide
How PDF highlights and annotations actually work
Highlighting should follow the text you selected—not force you to draw a rough rectangle over a sentence.
Text markup follows text geometry
A proper text highlight is usually a PDF markup annotation associated with the quadrilaterals occupied by the selected text. Multi-line selections therefore become multiple text-shaped regions instead of one large rectangle that can cover unrelated content.
Highlight, underline and strikeout are different review signals
Highlight is useful for emphasis, underline for calling attention without covering the glyphs, and strikeout for review workflows where text is proposed for removal. The underlying page text remains separate from the annotation.
Comments carry review context
A comment annotation stores a note at a page location. It is better for explanations, questions or review decisions than using visible text boxes as improvised notes.
Export and compatibility
After annotation, reopen the downloaded PDF in the viewer used by your recipient. Different PDF viewers render annotation appearances slightly differently, although the underlying annotation objects remain part of the PDF.