Purpose

[S]uccessful writing begins with having a motive for writing and understanding how that motive can be fulfilled. . . . [Motives include writing] to understand experience, to report information, to explain information, to evaluate something, to analyze images, to analyze texts, to persuade others, to inspire others, to amuse others, and to experiment with form.  Recognizing, through reading, the motives of other writers can help you discover your own sense of what you hope to accomplish when you write and so understand the principles likely to help you succeed.

Robert Keith Miller, Motives for Writing, pages 1-2

Each of the 10 chapters in Motives for Writing (the current English 111 textbook) addresses a different purpose for writing. 

Even after you have completed English 111, many of the writing assignments you complete in college may specify writing for a particular purpose.  The Longman Concise Companion helps students approach various writing assignments by providing a table of key verbs (such as analyze, argue, and discuss) and advice for responding to writing prompts that use these verbs.  See page 15.