permit; license; written permission
Refers to a physical or official document granting permission, such as a permit or license.
このエリアで撮影するには許可書が必要です。
You need a permit to film in this area.
許可証 is the tangible permit or card one carries as proof of permission, while 許可書 refers to the official written notice or letter granting that permission, often used in bureaucratic procedures.
immigration entry permit
business permit; business license
residence permit
re-entry permit
Compound of 許可 (permission) + 書 (document).