Marginalia is the general term for notes, scribbles, doodles and editorial comments made in the margin of a book. Marginalia can add or detract from the value of a book, depending on the book and the author of the marginalia. Marginalia in a Winston Churchill book by Tony Blair, for example, would add value; a student's notes in the margin of a Penguin edition of Oliver Twist would generally not.

There are notable exceptions in such fields as used textbooks. Scientists doing research on the future of the user interface have often studied the phenomenon of user annotation of texts. Looking at the impact of annotations on subsequent users of textbooks found at used book dealers, they discovered that in several university departments knowledgeable students would scour the piles for consistently annotated textbooks. The students had a good appreciation for the distillation of knowledge done by their predecessors.

In the last decade of the 20th century many attempts were made to design and market eBook devices permitting a limited form of marginalia. At the beginning of the new millennium the Sony Librie EBR-1000EP was introduced with a tiny but full qwerty keyboard below the display, to permit the creation of marginalia and bookmarks.

History's most famous marginal note is probably Fermat's Last Theorem.

External link

• Cambridge University Library marginalia pages