To all to whom these presents shall come, Greeting

A Letter Patent is an open letter (Litterae patentes) from the Monarch or Government, publicly proclaiming a right or grant upon an individual or corporation. The term Patent is a derivative of this, granting, as it does, rights which are to be publicly known. Forgery of letters patent in the United States of America is a federal offense punishable by up to 10 years in prison.

The College of Arms issues letters patent under permission from the monarch, which are illuminated vellum, which then become the property of the applicant. Letters patent are required in the United Kingdom for the creation of any government office, as the are for certain other countries which bear the same monarch as head of state. Obviously, they are not needed for most government jobs, only those where the job is actual governance. An example of the introduction to some letters patent follows below.

Passed under the Great Seal of the United Kingdom, constituting the Office of Governor and Commander-in-Chief of the Island of Newfoundland and its Dependencies.
Dated 28th March, 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, GREETING:
Whereas We did, by certain Letters-Patent under the Great Seal of Our United Kingdom of Great Britain and Ireland, bearing date at Westminster the sixth day of September, 1869, in the thirty-third year of Our reign, constitute and appoint Our trusty and well-beloved Colonel Stephen John Hill (now Sir Stephen John Hill, Knight Commander of Our Most Distinguished Order of Saint Michael and Saint George), Companion of Our Most Honourable Order of the Bath, to be, during Our pleasure, Our Governor and Commander-in-Chief in and over Our Island of Newfoundland and its Dependencies.