HOW TO: Remove Hidden Data in MS-Office® documents
When you create a document in a MS-Office® application (ie. MS-Word®, MS-Excel®, MS-Powerpoint®), it retains all of the modifications you’ve made during the creation of the document. It does this so that you can restore to a previous revision if need be, collaborate with others, etc. While this is a nice feature while you are editing a document, you might not want to include this content in the final product.