Writing for an Audience
Once you know your audience, you are ready to begin writing. Knowing your audience enables you to select or reject details for that specific audience. In addition, different audiences expect different types or formats for texts. Readers of Environmental Impact Statements don't want to read rhyming poetry extolling the virtues of nature. Mothers getting letters from children don't want to read a laboratory report about the events of the past month.
Knowing the knowledge level of your audience will help you determine how to write, how much information to include, how long to make your text, how subjective or objective you should be, and how formal or informal your text should be.