The Facebook Beacon refers to the agreement that Facebook has with popular online retailers. This agreement allows Facebook to utilize their users’ private information in ways that violate their privacy. When a Facebook user purchases something with one of the participating online retailers a message is sent to the user’s “friends” on Facebook, notifying them of the his or her purchase or transaction with that online retailer.

Facebook Beacon was meant to be optional; a buyer/Facebook user could choose to opt out of letting their friends know about their latest purchase. However, several instances have emerged in which personal information from the Facebook Beacon network was sent to the user’s friends without his or her approval. This is just one example of many ways in which social network sites have been working to monetize their user’s experience.