Careers in this field are practical by nature and involve the use of tools, machinery and equipment. People in these careers are more interested in getting on with the job, not spending time with the theoretical explanations behind the work. For this reason most of these careers have some aspect of manual labour and include tasks such as, building, fixing, constructing or producing. The choice of trade will depend on one's interests, the industry, materials used or level of complexity. For example, some people have a preference for one industry over another: aircraft, motor-manufacturing, building or printing. Alternatively, a person may like the materials used in that trade: wood (carpenter), metal (boilermaker), brick or stone (stonemason).