Summarize this article in one sentence.
Doing so will open the document in Microsoft Word. It's in the blue section at the top of the document's page. Doing so will open a new set of options related to editing your document. This option is at the top of the Word page, near the middle of the screen. Clicking it will enable Microsoft Word's "Track Changes" feature. Doing so will present you with the following editing options:   Simple Markup - Draws a vertical red line on the far left side of any added or deleted text, but shows no other edits.  All Markup - Displays all changes you make to your document in red text and comment boxes on the left side of the page.  No Markup - Displays your changes in addition to the original document, but no red text or comment boxes appear.  Original - Displays the original document without your changes. This option allows you to leave comments for other users to review if need be. This will highlight the text. You'll want to highlight everything on which you wish to leave a comment (e.g., an entire sentence or paragraph). It's near the center of the "Review" row of tools at the top of the Word window. It will appear on the right side of the Microsoft Word window. Doing so will cement your comment, allowing you to move on to the next section of text that needs commenting. Be sure to save your document before closing to make sure that your comments are preserved.

Summary:
Double-click a Word document you wish to change. Click the Review tab. Click Track Changes. Click the drop-down box next to Track Changes. Click All Markup. Click and drag your cursor across some text. Click the New Comment button. Type in your comment. Click anywhere on the document.