What is the drawing technique of using dots to create degrees of shading or solidity instead of using lines

In “a dream within a dream which phrase is a context clue to the meaning of grasp ?

He fields of graphic design and animation changed completely in a very short period of time in the late twentieth century. nearly everything that was once drawn by hand on a drafting table is now done on a computer screen. what are some of the advantages of this transition to digital techniques? are there any disadvantages? what are some of the skills that today’s graphic designers and animation engineers have that earlier ones did not? are there any skills that have been lost in the move to digital techniques?

In "thirty are better than one" 1963 by andy warhol describe to what degree this image depicts rhythm or pattern