What did you do with your book after the college entrance examination?

Books are the ladder of human progress, and when they serve mankind, they can really "retire". I used to like hoarding books, and I thought it was very stylish. But now I try to keep books to a minimum, and throw away all the books except the classic ones that need to be read repeatedly. The disposal method is mainly to sell or give away as waste. Why not sell it online? Mainly because old books are generally marked with lines and notes, the price is not high, and sometimes it is not even worth the freight, so it is not worth spending precious time and energy.