Erik Kwakkel, a medieval book historian at Leiden University and master tweeter on the subject of paleography and codicology, offers a 4-minute instroduction on how medieval script changed throughout the Middle Ages.
Kwakkel is also the subject of a discussion on the blog Burnable Books where its author, Bruce Holsinger writes:
Another such Twitter genius is Erik Kwakkel, a scholar of book history at Leiden University. Kwakkel’s day job involves the teaching of paleography (the study of old handwriting) and codicology (the study of old books) to students at all levels, at Leiden and elsewhere. His scholarly publications include several collaborative volumes on medieval books and readers as well as numerous articles on book history. Kwakkel’s Twitter feed (@erik_kwakkel) regularly provides links to ongoing discussions of medieval books, digital archives newly on line, and classroom exercises organized by himself and others (including the live tweeting of a hunt for manuscript fragments). He engages in regular Twitter conversations with colleagues in the field, sharing and commenting on links and images along with Sarah Peverley (@Sarah_Peverley), Kathryn Rudy (@katerudy1), Johan Oosterman (@JohanOosterman), Elaine Treharne (@ETreharne), Andrew Prescott (@Ajprescott), and other members of an emerging community of early book enthusiasts on Twitter.