Letters patent are a type of legal instrument in the form of a published written order issued by a monarch, president or other head of state, generally granting an office, right, monopoly, title or status to a person or corporation. Letters patent can be used for the creation of corporations or government offices, or for granting city status or a coat of arms. Letters patent are issued for the appointment of representatives of the Crown, such as governors and governors-general of Commonwealth realms, as well as appointing a Royal Commission. In the United Kingdom, they are also issued for the creation of peers of the realm.

A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention. In most countries, patent rights fall under private law and the patent holder must sue someone infringing the patent in order to enforce their rights.