If you are reading a book for a presentation or group discussion, you would want to mark the parts that seem important or worthy of comment. If you use a marker and highlight the passages, you may be left with the problem of finding the parts you marked when you are all finished. The regular Kindle, not the Fire as far as I can tell.
The regular Kindle creates a text file of the highlighted passages or the first part if a passage is very long. The user can look at the file from inside the book and move from passage to passage quickly and accurately using automatically generated links. All Kindles collect the highlighted passages from a book and transmit them to a web site kindle.amazon.com from which they can be viewed by the reader.
I have made highlights from the early pages of "Too Big To Know" and pasted them here.
The blog-web site The Millions has this opening to one of its articles:
From the Library of Your Soul-Mate: The Unique Social Bond of Literature
BY BRYAN BASAMANOWICZ
The bond formed around a favorite novel is one of shared immersive experience, usually open to impossibly wide interpretations. When we meet someone else who's "been there," there's a biting urge to know exactly what the other person saw, what scenes remain strongest in her memory, what crucial knowledge or insight was retrieved, and what her experience reveals or changes about our own?
For me, soul-mate or everyday intelligent and experienced reader, this is just the sort of insight I like from someone who has read a book I like, admire or detest. Highlights, especially from a Kindle, can furnish a great exploration of both a different view of a book and insights into a reader of interest.--
Bill
Main blog: Fear, Fun and Filoz
Main web site: Kirbyvariety