The range of documents requiring notarization varies from state to state, but generally speaking the common ones are:
Powers of attorney
Conveyancing documents in land and property transactions
Probate, wills and similar documents relating to the administration of estates of people
Personal documents and information for immigration control
Personal documents and information for overseas marriage
Authenticating company and business documents and transaction (e.g. shipping documents)
In general, any document that requires a secure record will require notarization.
Typically there are three broad categories of things a notary is used for:
Acknowledgments: You will likely need a notary to acknowledge a document at some point. Transferring ownership of real estate usually requires a notary, as does granting power of attorney or shifting control of a trust.
Jurats: A jurat is an oath in which you certify that the contents of a certain document are true. The oath is administered by a notary public and is often related to evidence presented in court.
Certifications of Copies (not all states): In some states, a notary has the ability to represent that a copy of a document is in fact an exact copy.
A Notary Public's background has been thoroughly checked, and they hold an office through the Secretary of State for the state their commissioned through.
Some Notary's have an office, others like myself are mobile. Which means I travel to you, be it your office, home, neutral location, hospital, even jails.
I AM NOT AN ATTORNEY LICENSEND TO PRACTICE LAW IN THIS STATE AND MAY NOT GIVE LEGAL ADVICE OR ACCEPT FEES FOR LEGAL ADVICE