Rhetorical modes describe the variety, conventions, and purposes of the major kinds of writing. Four of the most common rhetorical modes and their purpose are exposition

Expository writing

Expository writing is a type of writing where the purpose is to inform, explain, describe, or define the author's subject to the reader. Expository text is meant to deposit information and is the most frequently used type of writing by students in colleges and universities. A well-written...

, argumentation, description

Description

Description is one of four rhetorical modes , along with exposition, argumentation, and narration. Each of the rhetorical modes is present in a variety of forms and each has its own purpose and conventions....

, and narration

Narrative

A narrative is a constructive format that describes a sequence of non-fictional or fictional events. The word derives from the Latin verb narrare, "to recount", and is related to the adjective gnarus, "knowing" or "skilled"...

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The purpose of exposition

Exposition (literary technique)

At the beginning of a narrative, the exposition is the author's providing of some background information to the audience about the plot, characters' histories, setting, and theme. Exposition is considered one of four rhetorical modes of discourse, along with argumentation, description, and narration...

 (or expository writing) is to explain and analyze information by presenting an idea, relevant evidence, and appropriate discussion. Examples include:

• Business letter
  Business letter
  A commercial business letter is a letter written in formal language, usually used when writing from one business organization to another, or for correspondence between such organizations and their customers, clients and other external parties. The overall style of letter will depend on the...
  
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• How-to essays, such as recipes and other instructions
  How-to
  A how-to or a how to is an informal, often short, description of how to accomplish some specific task. A how-to is usually meant to help non-experts, may leave out details that are only important to experts, and may also be greatly simplified from an overall discussion of the topic...
  
  
• News stories
  Article (publishing)
  An article is a written work published in a print or electronic medium. It may be for the purpose of propagating the news, research results, academic analysis or debate.-News articles:...
  
  
• Personal letter
  Personal letter
  A personal letter is a type of letter which provides communication between a small number of people, usually two. There are many types of personal letters and they are written for a wide variety of reasons:...
  
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• Press releases
  News release
  A press release, news release, media release, press statement or video release is a written or recorded communication directed at members of the news media for the purpose of announcing something ostensibly newsworthy...
  
  
• Reports
• Scientific reports
• Term paper
  Term paper
  A term paper is a research paper written by students over an academic term, accounting for a large part of a grade. Term papers are generally intended to describe an event, a concept, or argue a point. A term paper is a written original work discussing a topic in detail, usually several typed pages...
  
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• Textbook
  Textbook
  A textbook or coursebook is a manual of instruction in any branch of study. Textbooks are produced according to the demands of educational institutions...
  
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• Wills
  Will (law)
  A will or testament is a legal declaration by which a person, the testator, names one or more persons to manage his/her estate and provides for the transfer of his/her property at death...
  
  
• Encyclopedia articles
  Encyclopedia
  An encyclopedia is a type of reference work, a compendium holding a summary of information from either all branches of knowledge or a particular branch of knowledge....
  
  
• Cuisines

The purpose of argumentation (also called persuasive writing

Persuasive writing

Persuasive writing, could be referred to as a creative writing or an argument, in which the speaker uses words to convince the reader of a writer’s view regarding an issue. Persuasive writing involves convincing the reader to perform an action, or it may simply consist of an argument convincing the...

) is to prove the validity of an idea, or point of view, by presenting sound reasoning, discussion, and argument that thoroughly convince the reader.