The whole writing process can be divided into three stages: prewriting, writing, and rewriting. In the prewriting stage, we try to get dear in our mind what our specific approach to the subject should be, what kind of materials we need, how these materials should be organized and presented to the particular reader we have these in mind. In short, we plan the organization and the content of our projected paper. In the writing stage, execute the plan by writing the first draft. In rewriting, we examine what we have done and consider where and how the first draft can be improved.
The three stages are not always separated as the previous paragraph may suggest. Sometimes, of course, they are separated, especially in working on long research papers. We may prepare extensive notes and draw several outlines before we begin the first draft, and then, perhaps days later, we may do a thorough revision of the draft. But sometimes, especially in writing short papers, we may plan and revise as we write. And often we may modify our original plan during the writing stage, as the actual writing modifies our ideas.