A commission is a formal document issued to appoint a named person to high office or as a commissioned officer in a territory's armed forces. A commission constitutes documentary authority that the person named is vested with the powers of that office and is empowered to execute official acts. A commission often takes the form of letters patent.

Commissions are typically issued in the name of or signed by the head of state. In Commonwealth realms, the documentation is referred to as a King's Commission or Queen's Commission (depending on the gender of the reigning monarch). However, in Commonwealth realms other than the United Kingdom, they may be signed by the governor-general, the representative of the monarch of that realm.

Because the word "commission" can also refer generally to an individual's duty, the more specific terms commissioning parchment or commissioning scroll are often used to specify the commissioning document. However, the document is not usually in the form of a scroll and is more often printed on paper instead of parchment. In Canada, there is a differentiation in terminology according to rank; officers are accorded commissioning scripts.^{[citation needed]}

Here is an example from Canada:

CHARLES THE THIRD, by the Grace of God, King of Canada and His other Realms and Territories, Head of the Commonwealth

To ........ .........

hereby appointed an Officer in His Majesty's Canadian Armed Forces

With Seniority of the .... day of ......... ....