Marginalia (plurale tantum) are notes, scribbles, and comments made by readers in the margin of a book, as well as marginal decoration,drolleries, and drawings in medieval illuminated manuscripts, although many of these were planned parts of the book. True marginalia is not to be confused with reader’s signs, marks (e.g. stars, crosses, fists) or doodles in books. The formal way of adding descriptive notes to adocument is called annotation.
Delicate sylvan decoration, hybrid beasts, and depraved humans engaging in irreverent acts seem counterintuitive to surround the pious content of a Book of Hours, yet between the mid-twelfth and fifteenth centuries, the margins of all types of medieval manuscripts were filled with ornate and curious imagery. How the medieval illuminator and reader understood and reacted to these images is unknown, though many hotly contested theories abound. Initially dismissed by scholars as purely decorative or simply the daydreams of an imaginative illustrator, marginalia is now interpreted by some as exemplifying how the sacred was defined in opposition to the profane within the rigidly hierarchical organization of the medieval world.
Some examples of medieval marginalia: