Drawing is fundamental to visual art. Three-dimensional art often begins life as a sketch on paper. Likewise, a doodle on a page can become the inspiration for a lithography. Drawing is also an end in itself, illustrated by the works of William Blake, and the more modern advent of cartoon, animation, and digital drawing.The line between what is drawing and what is painting can blur quickly. Drawings can have painterly elements and vice versa. For example, using techniques like shading and blending can greatly increase a drawing's sense of dimension, texture, and tonal value.The large variety of drawing instruments offers the artist scope and room for experimentation. The most common drawing instruments are pencils, pens, inked brushes, colored pencils, crayons, chalk, and pastels. Markers and spraypaint, however, are the drawing instruments of the graffiti artist, and the question of which two-dimensional surfaces are acceptable on which to draw provides diaolgue and controversy far beyond the walls of the museum.