Externality

What Does Externality Mean?
A consequence of an economic activity that is experienced by unrelated third parties. An externality can be either positive or negative.

Investopedia explains Externality
Pollution emitted by a factory that spoils the surrounding environment and affects the health of nearby residents is an example of a negative externality. An example of a positive externality is the effect of a well-educated labor force on the productivity of a company.