Each notary act such as an acknolwedgment, jurat, or certified copy must have an accompanying certificate. A notary certificate consists of standardized certificate wording including the name of the state, county, state specific boiler plate wording, and there is room for the notary's signature and seal's impression.
The certificate can be embedded in the document meaning that the words were printed on the last page of the document. Or, the certificate can be attached as a separate piece of paper to the back of the document.
Oaths and Affirmations as separate notary acts would not have a certificate unless done as a Jurat.