Who is my audience?
What do I want my audience to know or do during/after reading my message?
The answer to the second question will define your purpose for writing.
If you can’t provide an answer, you have two choices: One, begin to write and hope that a purpose comes to you—and then make note of it and use it as your guide. Or, two, meditate and percolate before you put fingers to keyboard or pen to paper.
The answer to the first question will define what your audience likely knows and doesn’t know about your subject. Thus, that answer will drive the content of your message, including the language you use and the amount of descriptive explanation you provide.
If, for example, you’re writing for an in-house audience such as company personnel, you can use trade jargon. If you’re writing a manual for the military, you can include military acronyms. However, if your material will be read by persons outside your company or not in the military, or even new employees or recruits, you will need to use civilian language and provide an explanation of uncommon terms.
The same consideration for audience knowledge is true when crafting a novel. If your story is set in New York City’s Times Square and your audience is American, you might casually mention “neon lights, massive electronic billboards, traffic and taxi cabs, and crowds standing in line for tickets to Broadway plays.” But if your story is about life in tribal Africa, that same American audience will likely want you to provide a greater description of environment, climate, scenery, cultures and customs, language and rituals, and so on.
Similarly, if you are attempting to educate African tribal people about New York City, you will need to build a foundation of knowledge that might include a description of tall buildings, paved roads and sidewalks, street lights, neon signs, and large masses of people. You might even need to provide details regarding ships and airplanes to help your readers understand travel from Africa to New York. And you would not use the term “The Big Apple” without thorough explanation.
Photo by Robert M Weir, January 2014, from a vessel piloted by Tasman Island Cruises, Tasman Island, Australia.