Book of hours
A book of hours is a prayer book for private use that contains a schedule of daily prayers and sometimes liturgy for the week, month, or season. Books of hours also sometimes included calendars. These books were very popular in the late Middle Ages and were often richly illuminated. One of the most well-known books of hours is the Très Riches Heures du duc de Berry.
Possibly one of the nicest early examples is the De Brailes Hours, which is covered in a modern book by Claire Donovan, which draws attention to the portraits of artist and intended owner delicately included.