In the United States a notary public is a person appointed by a state government (often the governor or the secretary of state of the state, or in some cases the state legislature) to serve the public as an impartial witness. Since the notary is a state officer, whether the jurisdiction is common law or civil law is determined on a state-by-state basis. In most states, only qualified persons can apply for such an appointment, called a commission. Qualifications vary from state to state, but states often bar people with certain types of criminal convictions and/or below a certain age from being appointed, and applicants usually must pass an examination covering notary practices and law. The material for such exams is typically contained in a booklet published by the state. Some states also require a bond or insurance.

Notaries Public (also called "notaries," "notarial officers," or "public notaries") hold an office which can trace its origins back to ancient Rome, when they were called scribae, tabellius or notarius. Their work would later be transcribed correctly in its entirety by a calligraphus. They are easily the oldest continuing branch of the legal profession.