Involves the use of computers in the design process. CAD software can be used to design two-dimensional (2D) and three-dimensional (3D) virtual models. It allows a business to simulate the product on a computer screen and to alter the specification, colour, features, in order to change the design, without ever having to build a prototype, thus minimising design costs. CAD is extensively used in the design of cars, ships and aeroplanes, as well as houses and commercial buildings. For example, architects can use CAD to simulate the design of buildings and assess the engineering requirements. They can also simulate individual rooms and take the customer on a ‘virtual tour’, which allows customers to modify their requirements if necessary. It is also used to produce computer animation for special effects in movies, advertising, and technical manuals. CAD reduces the cost and time involved in new product development (ie the lead time from idea conception to production). This makes it more affordable and feasible for a business to invest in new product development and to investigate, test and modify a greater number of ideas than in the past, and more easily investigate possible improvements to existing products. It enables more rapid response to changes in the market place ie changing customer needs and feedback, and competitor activities, which can be vital in helping a business to gain / maintain market share.