Writers need to consider both audience and purpose in writing because the two elements affect writing significantly, and decisions about one affect the other. For instance, a main purpose in advertising is to sell a product. Advertisers seek the audience who is most likely to purchase a product. Once they have identified this group [called the "target audience"], they can write their ads to capture the attention of this audience. Hence, their purpose, which is to sell a product or service, shapes what they write. Consider WHY you are writing.