In: Economics
Externality is the cost or benefit received by the third party due to the consumption of a product or a service. Here the third party is not involved directly in the consumption or production of that good or service. The third party can be anyone like an individual, organisation or a group of people.
Externality can be both positive and negative depending how it is affecting the third party we will decide whether it is a positive or a negative externality. If the third party receive a benefit due to externality than it is called a positive externality and if that third party have to Incurr costs than it is called as negative externality.
Ex: Positive externality: Google wants to upgrade with new technology it's Google maps which is a positive externality as people will can use that upgraded version of Google maps.
Negative externalities: Government gave permission for new companies for coal mining which is a negative externality as it increase pollution and affects the health of people.