With Books 3.0, a reader can customize it as they like.
In addition to turning off and on any of the feature discussed in this blog thread, the reader can easily add text annotations and notes.
Leave your mark with audio and text annotations.
See an example here.
Readers may annotate their book using either audio or text notes. Tap where you want to leave a note, speak your message into your phone (or enter text the old fashioned way), and save your annotation. An easy menu allows you to search and return to previous notes. Click an annotation and share it with your friends and colleagues. Never again will you have to thumb through little scraps of paper with your notes wedged into your book.
So if you find a piece of interesting information in CyberKill, you can annotate it for future reference or send your comments off to friends.