Who is The Reader from On Writing Well and what is their importance?

A writer should keep the reader in mind always—when actually writing, when thinking about writing, and when observing the world. A writer does not write for an editor. The writing is for the reader who expects certain things to happen. The reader wants to be drawn into a story and be entertained. The reader enjoys a particular writer's personality, and that personality should be consistent, at least in the sense that both the actual personality and writing personality are closely related and change together.