For a long time pdfLaTeX has offered the command \pdfannot for inserting
arbitrary PDF annotations. However, the command is presented in a form
where additional knowledge of the definition of the PDF format is
indispensable. This package is an answer to the - occasional - questions
in newsgroups, about how one could use the comment function of Adobe
Reader. At least for the writer of LaTeX code, the package offers a
convenient and user-friendly means of using \pdfannot to provide
comments in PDF files. Since version v1.1, pdfcomment.sty also supports:
LaTeX -> dvips -> ps2pdf, LaTeX - > dvipdfmx and XeLaTeX. Unfortunately,
support of PDF annotations by PDF viewers is sparse to nonexistent. The
reference viewer for the development of this package is Adobe Reader.