Although you might think editing and proofreading isn't necessary since you were fairly careful when you were writing, the truth is that even the very brightest people and best writers make mistakes, when they write. One of the main reasons that you are likely to make mistakes , is that your mind and fingers are not always moving along at the same speed, nor are they necessarily in sync, so what ends up on the page isn't always what you intended. A second reason is that, as you make changes and adjustments, you might not totally match up the original parts, and revised parts. Finally, a third key reason for proofreading is becthauset you most likely have errors; you typically make, and proofreading gives you a chance to correct those errors.