Any piece of writing is shaped by external factors before the first word is ever set down on the page. These factors are referred to as the rhetorical situation, or rhetorical context, and are often presented in the form of a pyramid. The three key factors–purpose, author, and audience–all work together to influence what the text itself says, and how it says it.
Any time you are preparing to write, you should first ask yourself, “Why am I writing?” All writing, no matter the type, has a purpose. Purpose will sometimes be given to you (by a teacher, for example), while other times, you will decide for yourself. As the author, it’s up to you to make sure that purpose is clear not only for yourself, but also–especially–for your audience. If your purpose is not clear, your audience is not likely to receive your intended message (read more).
In order for your writing to be maximally effective, you have to think about the audience you’re writing for and adapt your writing approach to their needs, expectations, backgrounds, and interests. Being aware of your audience helps you make better decisions about what to say and how to say it. For example, you have a better idea if you will need to define or explain any terms, and you can make a more conscious effort not to say or do anything that would offend your audience (read more).
The final unique aspect of anything written down is who it is, exactly, that does the writing. In some sense, this is the part you have the most control over–it’s you who’s writing, after all! You can harness the aspects of yourself that will make the text most effective to its audience, for its purpose (read more).
Voice is conveyed through the author's choice of diction or level of formality. It should directly connect to the text's audience and purpose.
In Defense of Rhetoric