Question

what is book illumination​

Answer 1

An illuminated manuscript is a manuscript in which the text is supplemented with such decoration as initials, borders (marginalia) and miniature illustrations. In the strictest definition, the term refers only to manuscripts decorated with either gold or silver; but in both common usage and modern scholarship, the term refers to any decorated or illustrated manuscript from Western traditions. Comparable Far Eastern and Mesoamerican works are described as painted. Islamic manuscripts may be referred to as illuminated, illustrated or painted, though using essentially the same techniques as Western works.