A ripple effect is a situation in which, like ripples expand across the water when an object is dropped into it, an effect from an initial state can be followed outwards incrementally.
Examples can be found in economics where an individual's reduction in spending reduces the incomes of others and their ability to spend.
In sociology, it can be observed how social interactions can affect situations not directly related to the initial interaction, and in charitable activities where information can be disseminated and passed from community to community to broaden its impact.
The concept has been applied in computer science within the field of software metrics as a complexity measure.
The concept has also been applied to financial markets to describe the impact of a given event and how it propagates through the players in the industry and its effect on stock price and stock coverage.