It depends on the document being notarized. When preparing a jurat, the person requesting the jurat must appear before the Notary Public, take an oath, and sign the document in the presence of a Notary Public. When preparing a certificate of acknowledgment, the document can be executed before the person brings for notarization. In an acknowledgment, the signer must personally appear before a Notary Public and acknowledge that the signer executed the document, not that the signer executed the document in the presence of a Notary Public. For both a jurat and an acknowledgment, the notary public must certify to the identity of the signer. (Civil Code section 1189 and Government Code section 8202)