It is an art period in Europe from approximately 1000 AD until the rise of the Gothic style in the 13th century. It was the first style that spread through the whole of Catholic Europe, from Denmark to Sicily.
It is a very vigorous style. The influence of the Byzantine style and Insular art is still visible. Yet, as the illuminated manuscripts of this time were now mostly Bibles or psalters, new scenes needed to be depicted. And this was done in originality. The decorations were lavish. The colors were striking and mostly primary. The compositions had little depth and were still in tight frames from which they tried to start to escape though. Figures still varied in size by their importance rather their position in the room. Portraits rarely existed.
This period sees the rise of the lay artist and craftsman. That’s due to the growing prosperity of Europe that made high quality art available to more than the royal courts and a small circle of wealthy monasteries.