MS Word: Track changes while you edit

You can easily make and view tracked changes and comments while you work in a document. By default, Microsoft Office Word 2007 uses balloons to display deletions, comments, formatting changes, and content that has moved. If you want to see all of your changes inline, you can change settings so that tracked changes and comments display the way you want.

Website: http://office.microsoft.com/en-us/word-help/track-changes-while-you-edit-HA001218690.aspx