If you are regularly sharing document and you want to add a personal touch to them or you do not want anyone to share them without your permission then you can add a watermark to them with a built-in feature of Word. On Word 2013 you will find the Watermark option in the Design tab. In 2010 and 2007 you will find it in the Page Layout tab. All versions offer the same options with the only difference being the location.
When you find the feature, click on it to expand the options. Here are some existing watermarks that you can choose from like “CONFIDENTIAL” and “SAMPLE” text watermarks. However, you can also add your own if you click on the custom option. You can either insert an image to be used as a watermark or use text. You can fully customize the images and the text before you add them so that they suit your needs. You can even opt to insert watermarks on specific pages only.
The only problem is that anyone can edit and delete the watermarks. You have to real options to prevent that. Either encrypt the documents to lock them down or share the Word documents as PDF files. You can easily save them in the PDF format if you go to File and choose to “Save as” PDF. If people really want to steal your documents this will not stop them but this will make it that much harder for them, especially if they are not careful.