A proposal is a document written to persuade the reader to accept a plan or course of action. Proposals analyze needs or problems, present solutions, and persuade the audience that the proposed solution is best. Proposals can be internal or external, and solicited or unsolicited. Internal proposals seek approval within an organization, while external proposals seek approval from clients or officials. Solicited proposals respond to requests, and unsolicited proposals attempt to obtain business without invitation. Proposals vary in length and structure but typically include an introduction, body, and conclusion for short proposals or additional front and back matter sections for long proposals.