A notary public acts as an impartial third-party witness to not only the signature of a document, but also that all parties who signed a document did so willingly and under their own free will.
Types of documents that may require notarization
A valid, government issued photo ID is required. Laws vary by state and some documents may require witnesses in addition to the notarization. In most cases, the notary cannot act as a witness. If your document requires a witness, please make arrangements for one.
Any source document. For example, birth certificates, copies of passports, etc.