Externalities

"Externalities are the situations where persons impact upon each other in ways that are not intermediated through voluntary agreements between these persons, where people impact upon each other in ways that were not negotiated." (Kelkar and Shah 2019:18)

"Whether positive or negative, externalities involve gains or harms that are imposed upon bystanders, which do not directly feed back upon decision makers through the normal market process" (Kelkar and Shah 2019:18)