I grew up using the library, so I learned to do my best to keep books in the best condition possible. When studying I've underlined and highlighted, but those were all books I planned to refer back to often.

I will say that I was ready to rip the Wheel of Time books in half. They are so large, the print is so small and it hurt my hands to hold them open for so long. I bought the first in the series new and there are several creases in the spine now.