A permission letter is a formal request for approval to undertake a specific action or access certain resources. It typically outlines the requester's name, the purpose of the request, and the details of what is being sought, such as time off, access to facilities, or approval for a project. The letter includes a rationale for the request and any supporting information that justifies it. Its tone is polite and professional, aiming to convey the request clearly while demonstrating respect for the decision-maker's authority.