Assume that you intend to publish your eBooks in portable document format. Could it be that someone is trying to get hold on the information that belongs to you and wants to use for their own good? This could be easily done by any third party if your documents are not protected against such infringements or violations.
There are various features bundled in various tools that help users to keep their data safe from others. PDF is a format that had been introduced by Adobe systems with the intent to make it easy for users to share their files with others over the Net.