This flexible term describes the variety, the conventions, and the purposes of the major kinds of writing. The four most common rhetorical modes (often referred to as "modes of discourse") are as follow:
A. The purpose of exposition (or expository writing) is to explain and analyze information by presenting the idea, relevant evidence, and appropriate discussion. The AP language exam essay questions are frequently expository topics
B. The purpose of argumentation is to prove the valdity of an idea, or point of view, by presenting sound reason, discussion, and argument that thoroughly convince the reader.
Persuasive writing is a type f argumentation having an additional aim of urging some form of action
C. The purpose of description is to recreate, invent, or visually present a person, place, event or action so that the reader can picture that being described. Sometimes an author engages all five senses in description; good descriptive writing can be sensuous and picturesque. Descriptive writing may be straightforward and objective or highly emotional and subjective
D. The purpose of narration is to tell a story or narrate an event or series of events. Tis writing mode frequently uses the tool of descriptive writing