Process
Drawing, as it was practiced in the western tradition, emerged from the Renaissance, when far-reaching changes in artistsı methods of design and execution took place. In the middle ages drawings were either finished records of compositional ideas that were kept in model books, underdrawings beneath frescoes and panel paintings, or working sketches on wax tablets or fragments of plaster and pottery which have not survived. Beginning in the early fifteenth century the increasing use of motifs observed from nature, the study of antiquities, and complex compositions based on mathematically consistent perspective required preparatory drawings that solved each problem individually and assembled them into a whole.

The availability of paper as a relatively affordable support for drawing provided the means that made this expansion the functions of drawing possible. Hence, from the Renaissance to the beginning of the twentieth century, most drawings served a specific preparatory function in the development of the artistıs concept from first idea to finished composition. Each sheet had its place in a series of working drawings, and there was usually some technical means of transferring the design from one sheet to another, as the artistıs thought progressed from one stage to the next.
 
 Underdrawing  Offset, or counterproof
 Incision  Squaring
 Overlays  Pouncing
 

by Michael Miller
Information supplied by: http://www.nyu.edu/classes