What is external spillover benefits?

External spillover benefits refer to positive effects experienced by third parties or the broader community as a result of an individual's or organization's actions, without those parties having to pay for those benefits. For example, when a company invests in green technology, the surrounding environment and local population may benefit from reduced pollution and improved air quality. These benefits are not reflected in the market transactions and often lead to increased social welfare. Essentially, they highlight the broader positive impact of certain activities beyond the direct participants.