When you pick up a book to read, do you also pick up a pencil, ready to mark up the margins with your thoughts and ideas? If so, your written additions are part of a body of writings called marginalia. For many readers, scribbling on the pages of books is a beloved, recreational practice. For others, it’s more of a necessity. Whether they are humorous jots and tittles, lessons learned from the story, or more serious notes of textual analysis, marginalia are simply fascinating.