I love that, I have never received an annotated book before but I kind of want one know 🙈

I sometimes do this and it’s often to mark sentences that stood out to me. Mostly because they were just really beautiful and I want to be able to reread them again later. But you can also underline a sentence because it’s relatable or because you found it funny or something like that. If you look up videos on why people annotate books you might find better examples and instructions