This is probably the most common use of the notary. Authenticating contracts and legal documents that deal with anything concerning estates is one of the most common practices that need legality and validity. Such documents include tax certificates of the land, tax declarations of the estate, certificate of ownership, land title and other some such documents that deal with anything concerning a land or a property. Authentication of such documents is of paramount importance to both parties in the dealing, especially if it involves any kind of buying or selling.