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The term leakage has numerous definitions:

• In normal usage, leakage is the diffusion of energy or matter out of a container.
• In chemistry, leakage refers to the loss of chemicals, usually undesirable.
• In electronics, leakage means the gradual loss of energy from a cell or capacitor stored with high chemical energy.
• In retail trade, leakage means a loss of stock.
• In semiconductors, leakage refers to a process where electrons stray from their desired path.
• In sound recording, leakage (also called spillage) occurs when audio intended for one track is picked up inadvertently by another track's microphone.

Chemistry

In chemistry, leakage is a process in which material is lost, intentionally or accidentally, gradually through the holes or defects of their containers. Often, leakage can be disastrous if the leaked material is harmful or corrosive.

A zinc-carbon battery is an example of an easy-leaking system. The electrolytes inside the cell sometimes leak out of the cell shell, and cause damage to an electronic appliance.

Electronics

In electronics, leakage is a property of dielectric materials used in capacitors, also known as dielectric leakage. It is a result of the dielectric material having a finite resistance and therefore carrying a current (known as the leakage current) due to the voltage across it. This results in capacitors discharging themselves over time (analagous to a bucket full of water with a hole in it, the size of the hole relating to the amount of leakage).

The dielectric material can be selected to have low leakage, which may be required for some electronics applications such as sample and hold circuits.

Retail

Retail leakage occurs when members of a community spend money outside that community or when money spent inside that community is transferred outside the community. For example, crossing a border to buy goods forgoes the same purchase that could have been made inside the community. Many chain stores have high leakages rates due to the transferring of sales revenue to a corporate headquarters. Also, in retail, leakage can mean the loss of stock without a compensating stream of revenue, for example, a till operator stealing from a till, or a shoplifter stealing stock.

Semiconductors

In semiconductor devices, leakage is a quantum phenomenon where electrons tunnel through an insulating region. Leakage increases exponentially as the thickness of the insulating region decreases. The primary source of leakage occurs inside transistors, but electrons can also leak between interconnects. Leakage increases power consumption and if sufficiently large can cause complete circuit failure. Leakage is currently one of the main factors limiting increased processor performance. Efforts to minimize leakage include the use of strained silicon, high-k dielectrics, and/or stronger dopant levels in the semiconductor. Leakage reduction to continue Moore's law will not only require new material solutions but also proper system design. A good overview of leakage and leakage reduction methods are explained in Leakage in Nanometer CMOS Technologies

Sound Recording

Multitrack recording is at its optimum when there is sufficient isolation between individual tracks, to allow for freedom in remixing each track to a desired sound level. Reasonable isolation can be achieved (even in a live recording) by careful microphone placement, or by the separation of sound sources. Sound leakage can limit or even ruin the remixing and overdubbing potentials for a multitrack recording, when one sound interferes with another sound on a track.

• Electronics
• Chemical processes
• Distribution, retailing, and wholesaling
• Sound recording