Title: Air gap (plumbing)
Content:  into the potable water system by siphonage and is the least expensive form of backflow prevention. A common use of the term "air gap" in home plumbing refers to a fixture that provides back-flow prevention for an installed dishwasher. This "air gap" is seen above the sink as a small cylindrical fixture mounted parallel with the faucet. In the base cabinet under the sink, the drain hose from the dishwasher feeds the "top" of the air gap, and the "bottom" of the air gap is plumbed into the sink drain below the basket, or into a garbage disposal unit. When installed and maintained properly, the air gap works as 
Title: Air gap (plumbing)
Content:  above, and prevents drain water from the sink from backing up into the dishwasher, possibly contaminating dishes. To further illustrate the air gap, consider what could happen if the air gap were eliminated by attaching a hose to the faucet and lowering the hose into a sink full of contaminated water. Under the right conditions (if the water supply loses pressure and the sink is higher than the point at which the water supply enters the house, for instance), the dirty water in the sink will be siphoned into the water pipes through the hose and faucet. The dirty water then will be dispersed throughout the drinking water system.
Title: Air gap (plumbing)
Content:  An air gap, as related to the plumbing trade, is the unobstructed vertical space between the water outlet and the flood level of a fixture. Air gaps of appropriate design are required for water safety by legislation in many countries. A related term in computer security is network air gap. A simple example is the space between a wall mounted faucet and the sink rim (this space is the air gap). Water can easily flow from the faucet into the sink, but there is no way that water can flow from the sink into the faucet without modifying the system. This arrangement will prevent any contaminants in the sink from 
Title: Air gap (plumbing)
Content:  plumbing fixtures. A common misconception is that a "high loop" (routing a drain line above a sink's flood level, for instance) will provide the same function as an air gap; this is not true, because the continuous connection in such a case still will allow backflow through siphoning. According to the International Residential Code 2003, an air gap must meet the requirements of being two times the effective inner diameter of the pipe (2×D) in order to be sufficient. A standard widely use in the United States is:  In the United Kingdom, legislation is by statutory instrument and vary by country, but include Water Supply (Water Quality) Regulations 2016 and Water Supply (Water Quality) Regulations (Wales). The categorisation of air gaps is standardised by European standards, which cover the basic design and dimensions for appropriate to different uses.
Title: Air gap (networking)
Content:  An air gap, air wall, air gapping or disconnected network is a network security measure employed on one or more computers to ensure that a secure computer network is physically isolated from unsecured networks, such as the public Internet or an unsecured local area network. It means a computer or network has no network interface controllers connected to other networks, with a physical or conceptual air gap, analogous to the air gap used in plumbing to maintain water quality.
Title: Dishwasher
Content:  exposed element. European machines and some high end North American machines use passive methods for drying – a stainless steel interior helps this process and some models use heat exchange technology between the inner and outer skin of the machine to cool the walls of the interior and speed up drying. Most dishwashers feature a drying sensor and as such, a dish-washing cycle is always considered complete when a drying indicator, usually in the form of an illuminated "end" light, or in more modern models on a digital display or audible sound, exhibits to the operator that the washing and drying cycle is now over. Governmental agencies often recommend air-drying dishes by either disabling or stopping the drying cycle to save energy.
Title: Backflow prevention device
Content:  The simplest, most reliable way to provide backflow prevention is to provide an air gap. An air gap is simply an open vertical space between any device that connects to a plumbing system (like a valve or faucet) and any place where contaminated water can collect or pool. A simple air gap has no moving parts, other than flowing water. Many plumbing codes specify a minimum air gap distance required for various circumstances, such as a drain connection for a dishwasher, e.g., BS 6282. Alternatively, a specialized backflow preventer valve may be installed at strategic locations in the plumbing system wherever there is a risk of contaminated fluids entering the water supply pipes. These valves are used where there is not sufficient vertical clearance or physical space to install an air gap, or when pressurized operation or other factors rule out use of an air gap. Because these valves use moving parts, they are often required to be inspected or tested periodically.
Title: IBM airgap
Content:  Airgap is a technique invented by IBM for fabricating small pockets of vacuum in between copper interconnects. The technique belongs to a general class of similar techniques that replaces solid low-k dielectrics with air-filled or vacuum pockets.
Title: Dishwasher
Content:  conservation features in dishwashers. One feature was use of "soil sensors", which was a computerized tool in the dishwasher which measured food particles coming from dishes. When the dishwasher had cleaned the dishes to the point of not releasing more food particles, then the soil sensor would report the dishes being cleaned. The sensor operated with another innovation of using variable washing time. If dishes were especially dirty, then the dishwasher would run for a longer time than if the sensor detected them to be clean. In this way, the dishwasher saves energy and water by only being in operation for as long as needed.
Title: Dishwasher
Content:  The heat inside the dishwasher dries the contents after the final hot rinse; the final rinse adds a small amount of rinse-aid to the hot water, as this improves drying significantly by reducing the inherent surface tension of the water. Plastic and non-stick items form drops with smaller surface area and may not dry properly compared to china and glass, which also store more heat that better evaporate the little water that remains on them. Some dishwashers incorporate a fan to improve drying. Older dishwashers with a visible heating element (at the bottom of the wash cabinet, below the bottom basket) may use the heating element to improve drying; however, this uses more energy. North American dishwashers tend to use heat-assisted drying via 

Question: what does the air gap do on a dishwasher?
Answer: backflow prevention.