When you want to store a PDF document in an archive or simply provide more information, it is useful to update its document information or metadata. This includes things such as the author's name, and keywords relating to the document's content. Including appropriate metadata makes it that much easier to index your PDFs, and hence, easier to find them again later. This tip explains how to update a PDF document's metadata in Acrobat.
In order to update a PDF's metadata:
Open the document in Acrobat.
Select File > Document Properties.
In the Description section, enter the desired text in the title, author, subject and keywords fields.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.