Chaff refers to large quantities of passive reflecting material
deployed in the atmosphere to counter or confuse enemy radar.
Chaff was (almost) simultaneously introduced during World War II
(1943) by the Germans and the British. The British called
their version of chaff window.
In terms of functionality, chaff is capable of providing a form of camouflage from
the radar system. Chaff can be deployed extensively and
cooperatively by a number of platforms to produce a cloud
through which the radar cannot penetrate. Some radar systems are
confused by clouds of chaff whilst others sense the
chaff clouds as false targets.