Art history is an academic discipline dedicated to understanding artworks in their historical and cultural contexts. Analysis of artworks can be formal, focusing on visual elements, or contextual, examining outside influences. Important periods include the Romanesque, with barrel vaults and flying buttresses, and the Renaissance, where linear perspective and sfumato were developed. The Reformation and Counter Reformation impacted dramatic religious art. Color theory concepts include hue, value, intensity and color schemes. Composition principles include balance, rhythm, focal points and proportion. Printmaking techniques include relief, intaglio, engraving, etching and lithography. Painting methods include fresco, glaze, encaustic and gouache. Pottery construction uses slab