When used in homes, computers face the challenges of dust accumulation, accidental exposure to liquids or moisture and accidental impact. In industrial settings, computers are exposed to similar hazards but to a greater extent. Especially in heavy manufacturing settings, computer enclosures must be able to protect sensitive components from flying or settling debris, inhospitable temperatures and exposure to moving machinery and workers. Computers mounted in vehicles must be resistant to constant vibrations and impact, so their enclosures can be designed to include elaborate suspension systems. Because there are so many different varieties of computers, a wide variety of enclosure configurations exist to accommodate that variety. Laptop computers, for example, must be designed with materials that are light enough to prevent the computer from becoming cumbersome but sturdy enough to protect the computer.
Computer enclosures are made out of a range of materials; aluminum and stainless steel are commonly used in metal enclosures, especially in computer models in which weight and portability are not important considerations. Most laptops are made of a durable plastic like ABS (acrylonitrile butadiene styrene), though some are made from thin, lightweight metals. A computer enclosure's suitability for a given application is determined by standards setting organizations, one of the most prominent of which is the National Electronics Manufacturers Association (NEMA). NEMA gives ratings to configurations that professionals can use to determine whether or not an enclosure is suitable for a given application. For example, NEMA enclosure types 1, 2, 12, 12K and 13 are rated for indoor uses in which exposure to hazards like impact and contaminants is not likely. They also issue ratings for enclosures rated for low-hazardous outdoor use, high-hazard indoor use, and high-hazard indoor or outdoor use. The International Electrotechnical Commission also issues ratings for computer enclosure based on their expected performance in a range of contexts. Custom enclosures are built by hobbyists for personal use and by professionals for use in unusual applications; computers designed for use in laboratories must often be developed to function in less than hospitable environments. In those and other unusual cases, enclosures can be built to resist interference and other harmful environmental presences.