Gurpreet Singh The term " Marginalia" sounds like a simple word, but actually packs some interesting dimensions of reading, learning and history. Marginalia are often left by readers who can be unique insights into the minds of readers from different eras in the margins of books, manuscripts, and documents. What is Marginalia? Marginalia are comments, notes, drawings, highlighting or similar in the margins of a text. These annotations are typically made by the readers who reads the text.