Facebook has changed advertising in 3 key ways:
1) Facebook ads allow for highly targeted advertising based on users' social media activity and interests. This precise targeting makes ads more effective.
2) Brands can engage with customers on Facebook through pages, polls, and virtual promotions. High customer engagement on Facebook pages leads to increased brand loyalty and sales.
3) The widespread adoption of social plugins like the "Like" button has integrated Facebook engagement into the majority of top websites. This has increased the volume of user data Facebook can collect and allowed them to develop new advertising products like OpenGraph.