Externalities

Definition

Unintended side effects (can be good or bad) to those not involved.

Origin

Two British economists are credited with developing the conceptual models and economic studies of externalities in the 19th century — Henry Sidgwick and Arthur C. Pigou (source).

Everyday Use

There are hidden costs to everything that we do — from perpetuating bad habits to going out of our way to express gratitude. Not only is it hard to register the weight of these activities in the moment, it's nearly impossible to understand all the downstream effects that are beyond our radar.