I don't use either. I memorize the page number. You can tell how much I like a book by the condition it's in. The more perfect a book appears, the higher up on my list of favorite books it is. I haven't let anyone even so much as touch TFiOS (except for me)... I always feel like I'm the opposite of 90% of the world. I can't stand book marks or dog-eared books.
I try to memorize the page numbers, but I read anywhere from 6-10 books at one time and it get's to complecated.
When I read a lot of books that happens sometimes too. On occasion I write down the numbers somewhere so I don't forget which book is which.
I bookmark my books, but once I've read them once, I go through and find my favorite parts and dog-ear those pages.
I'm a find-a-random-scrap-paper-bookmarker, although I do occasionally memorise page numbers.
Neither... got a kindle :P
touche Benny. touche
I've got one too but I have a backlog of books I have to read before I'm gonna use it.
I have a dirty habit of dog-earing, but I try not to. I only highlight/underline in John Green books because when I want to reread some wise quotes, I know just where to go.
I dog-ear my books, I think It is a sign of love but I think that writing/highlighting books is terrible and refuse to do it. That said there is one book that I have, my Harry Potter and the Deathly Hallows that I got the night it came out. I completely destroy it. I've read that book more times than I have any other. 43 on my last count and I LOVE it. I use it almost as a diary now. I write in the margins, do charcoal sketches, it has coffee stains, tea stains, tear stains, you name it. If an outside looked at that book they'd think it went through some sort of natural disaster, but I just show my love on it.
I only dog-ear when I want to remember where something happens for class. If it's a favorite I refuse to even break the spine. I give people a list of rules to follow if allow them to borrow a book of mine. That includes no dog-earring. I feel like the book is ruined then. Books for class though... all about dog-earring and marginalia.
I always use book marks, I dont have anything against dog-earing. I just instinctevly dont. Plus my Grandmas, Aunties relitive of some sort gave me a supper nice one.