Anyone do it? Is it considered Sacrilegious? I'm thinking about doing it to a few of my books, just to show my thoughts to any children I may have...
Back in college, I did annotate a couple of books we read for class. It made finding passages for essays and assignments a lot easier. I didn't really care about doing it since the books were old and falling apart anyways. In general, I don't annotate. If I really need to remember something, I'll use a sticky note.
Personally, I don't do it, because I have a silly thing about trying to keep my books looking in mint condition -- looking brand new, and unread, no creases in the spine or folds in the page. I know others like it, because they enjoy the notes, and if they subsequently give away or sell the book, they like the idea that others can read their thoughts, as they like finding others thoughts in used books that they have acquired. However, a woman I know just complained about this very issue -- she writes all kinds of notes inside the front cover, and when she went to give the books to the library, they were mad that it had been written in and claimed that they would not be able to sell it for that reason. I can see liking the notes/thoughts/reactions in a book, especially if it were a book that was owned by someone I know, such as a parent or grandparent. So, I can understand why someone would do it. I just don't because of my thing with keeping the books pristine. (Which also makes it hard for me to lend books, because I really don't like it when someone is not as careful as I am with my book.)
Apart from that, I prefer to form my own opinions from what the writer created. I don't want to be distracted by someone else's musings in the margins (and I don't care for shows like MST3K either).
I like to collect antique books, pre-20th century only. Not to read, as such, but I treasure them as objects. The look and feel and smell. The history. Many of my books have notes and annotations, hundreds of years old, in scrawling ink-well cursive. It really adds to the charm in my opinion. There are 'blank' pages at each end of the text with long letters to people, dot point notes about their thoughts on various pages, some have notes and thoughts from school children, and there are numerous dates, names, to and from, often in the same book spanning decades and centuries. Some may consider it vulgur to write in a book today, but if that book ends up in someone's antique collection in 1-2-3 hundred years time, your scribbles could be a fascinating treasure. I say, if you want to, do it.
I annotate all of the books I read for my college courses, but I vary how extensive I do it based on whether I plan on keeping the book. For books that I know fit into my thesis and my future scholarly work, I annotate a lot, with highlights, underlines, and notes in the margins. For books I know I don't care about and will sell at the end of the semester, I just underline or highlight for easy reference but without ruining the overall value for another student.
I would never even think of writing in a paper book. But when reading e-books, I like to attach a note now and then or highlight some passages.
I once annotated entirely through The Sound and the Fury. Overall, it was worth it. The state of the book was somewhat abused, and I think I picked it up for $3.99. So, no big deal really. Plus, it helped me to understand those confusing stream-of-consciousness passages. Honestly though, I wouldn't recommend it unless you're doing it for school or the work is philosophical in nature. Most contemporary novels probably wouldn't require it.
I'll highlight and make notes on e-books, like if they reference another book and I think I'll want to read it I'll highlight it but I never do it in paper books normally, apart from one book of quotes where I highlighted my favourite ones. If I'm reading technical books then I'll highlight and annotate them to my heart's content whether they're paper or not.
In high school I developed a habit of annotating books due to the extract analysis work we had to do in Literature. My books were literally falling apart having been read so much, highlighted passages and scribbles of ink everywhere. I still have those books in my shelf and I would never replace them for any copy in the world because of how much effort I went into doing it, and how much fun I had losing myself in the puzzle of a book's intricate themes and motifs. I don't do this anymore, and now I simply read for pleasure. However, now that I have a kindle I will occasionally highlight a passage of text that I think was particularly well written, simply so I may refer to it one day for inspiration. When it comes to philosophy or psychology books I always have and always will highlight and annotate, as those books require you to be active with your thinking in order to get the most out of them. It helps with the consolidation process of information from short term to long term memory by highlighting a useful piece of information and also makes it easier to skim through the book and re-assimilate its most important parts.
I would never deface a book in such a manner. Like chicagoliz, I keep my books looking brand new. I open Word document files in which to type particular passages that I like, highlight certain parts and write my comments beneath the quoted passage. It's also there for me to copy and paste if I need to refer to it during a discussion if it's pertinent to the topic.
I've read books with annotations in them before, and really enjoyed being able to see another person's thoughts on the story. In some places the notes even helped me understand parts of the narrative that I'd been struggling with.