What's a Notary Public?

What the book says:
     A Notary Public is a public servant appointed by state government to witness the signing of important documents, acknowledgments, administering oaths and affirmations, and performing other acts authorized by law.
 
What the book means:
     An impartial witness (the Notary) identifies signers to screen out impostors and to make sure they have entered into agreements knowingly and willingly. In other words, the purpose of a notary is to identify the person signing a document to screen out identity fraud, and to prevent forgery of signatures.
 
A Notary Public is NOT an attorney and, therefore, cannot give legal advice about immigration or any other legal matters.