Many people use stamps as part of their documents to mark them as approved or completed. For example, when a document is to be signed by the concerned person at a company, he puts his signature as well as stamps the document as a proof that the document is signed by the authorized person. In other words, the stamps are used to seal the document that is being exchanged among multiple persons/parties....at a company, he puts his signature as well as stamps the document...Various companies use digital signatures to sign their document...