A decoy is usually a person, device or event meant as a distraction to conceal what an individual or a group might be looking for. Decoys have been used for centuries most notably in game hunting, but also in wartime and in the committing or resolving of crimes.

The decoy in war may for example be a wooden fake tank, designed to be mistaken by bomber plane crews to be real, or a device that fools an automatic system such as a guided missile, by simulating some physical properties of a real target.

For a defence system, decoys and chaff for ICBMs would mainly work in midcourse: during the boost phase they would be inside the rocket, because separate rockets for each of many decoys would not be practical, while at reentry light decoys and chaff considerably slow down and/or are destroyed in the atmosphere. main: Duck decoy A decoy was originally a small pond with a long cone-shaped wickerwork tunnel, used to catch wild ducks. After the ducks settled, a small trained dog would herd the ducks into the tunnel. The catch was formerly sent to market for food, but now these are only used to catch ducks to be ringed and released: see ornithology. The word came from Dutch eende(n)kooi = "duck cage". As the above meaning of a person or device supplanted the original meaning as the most common, the latter acquired the retronym "decoy pool". List of Duck Decoys

Wildfowl decoys (primarily ducks, geese, shorebirds, and crows, but including some other species) are considered a form of folk art. Collecting decoys has become a significant hobby both for folk art collectors and hunters. The world record was set in January 2007 when a red-breasted merganser hen (circa 1875) by Lothrop Holmes of Kingston, MA sold for $856,000(US).

In biochemistry

In biochemistry, there are decoy receptors, decoy substrates and decoy RNA. In addition, digital decoys are used in protein folding simulations.

Decoy receptor

A decoy receptor, or sink receptor Pleiotropic Action of VEGF in the CNS, is a receptor that binds a ligand, inhibiting it from binding to its normal receptor. For instance, the receptor VEGFR-1 can prevent vascular endothelial growth factor (VEGF) from binding to the VEGFR-2

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Decoy substrate

A decoy substrate or pseudosubstrate is a protein that has similar structure to the substrate of an enzyme, in order to make the enzyme bind to the pseudosubstrate rather than to the real substrate, thus blocking the activity of the enzyme. These proteins are therefore enzyme inhibitors.

Examples include 3KL produced by vaccinia virus, which prevents the immune system of phosphorylating the substrate eIF-2 by having a similar structure to eIF-2. Thus, the vaccinia virus avoids the immune system.