The revision process: Looking back and moving forward
Editing a document often takes up at least as much time as producing the first drafts of an essay. The goal is to ensure that you’ve completed all of the necessary tasks and that the essay is as well-articulated as possible.
Some writers edit as they write, completing a few paragraphs or a section, and then reworking these paragraphs or sections. Other writers save the bulk of the editing for after they are reasonably certain that they have no more information to add to the paper. Whatever degree of editing you do while you write, though, you will need to make a few more passes through the document once it is more or less complete.
And whether you prefer to alternate between writing and editing or to save editing for the end, you will need to look for the same sorts of things as you edit, keeping in mind both global concerns and fine-grained details.