What is the difference between certifying and signing a document?
Certifying a document When you save an Adobe® Acrobat® PDF document as certified, you attest to its contents and specify the types of changes that are permitted for the document to remain certified. For example, suppose that a government agency creates a form with signature fields. When the form is complete, the agency certifies the document, allowing users to change only form fields and sign the document. Users can fill in the form and sign the document, but if they remove pages or add comments, the document is no longer certified. When you certify an Adobe PDF with a VeriSign issued CDS certificate (that has not been revoked), a blue ribbon icon will appear next to the digital signature and in the Signatures tab. Signing a document A digital signature can be either visible or invisible. A visible signature appears in both the document and Signatures tab. An invisible signature appears only in the Signatures tab. Adding a signatures does not affect the validity of existing signatures
