Cascade

Cascade is a term used to describe a sequence of events in which the output of one step triggers the next. In everyday language it also denotes a waterfall or a series of waterfalls. The word comes from French cascade, from Italian cascata, meaning a fall of water.

In the natural world, cascades describe systems where effects propagate through layers. A cascade of waterfalls is a river feature. In hydropower, a cascade refers to a set of dams or power stations located along a river, connected so the output of one drives the next. In science, cascade processes include chain reactions in chemistry or particle interactions in physics, where products become reagents that produce more products. In ecology, trophic cascades describe how changes at one level of the food web can affect multiple other levels.

In technology, cascades are multi-stage processes in which information or control signals pass through successive layers. Cascade control loops link a primary controller to a secondary controller to improve stability. Cascade classifiers are sequences of models used in image analysis to progressively reject unlikely candidates. Cascading style sheets (CSS) use a hierarchy of rules where later rules can override earlier ones to determine presentation.

Cascading effects also appear in engineering and networks when an initial fault propagates, potentially causing widespread failure. The term is widely used in business and information dissemination to describe how policies or announcements cascade through organizations.