Computers these days are used in every field like in Offices (word processing, spreadsheet and accounting packages for a paper less office.), Publication and Printing (Design, layout and composition of books, brochures, visiting cards, letter heads using popular packages like PageMaker, CorelDraw, etc. and popularly known as desktop publishing.) and Computer Aided Designing (Engineers, scientist and designers use Computer Aided Design (CAD) software to design a machine, car, building etc. These designs can be viewed in 3D before the production of machines. Computers can also control manufacturing machines like drill, lathe machines by computer aided manufacturing (CAM)).