Post Office Notary Service is a legal service offered by the United States Postal Service (USPS) to authenticate documents and provide verification of signatures on documents. It provides customers with the assurance that the signature on their document is valid and legally binding, as it has been certified by an authorized USPS representative. The process involves signing a document in the presence of a Notary Public or other authorized individual who will then witness and sign the document. Through this service, individuals and organizations alike can ensure that the signature on their documents are valid and enforceable.