Did you notice that the writing style, organization, content, and language of each example varied?  That’s because the writer’s purpose “is like a filter through which every word to be included in the written communication must pass” (Polnac 3). 

You will be expected to filter your writing style, organization, content, and language as you write essays for different purposes.  Therefore, it is important for you to become familiar with the characteristics of each purpose. 

In addition, understanding the characteristics will help you identify the writer’s primary purpose.