Feed following
Adam Silberstein, Ashwin Machanavajjhala, Raghu Ramakrishnan · Databases and Social Networks · 2011
Internet users spend billions of minutes per month on sites like Facebook and Twitter. These sites support feed following, where users "follow" activity streams associated with other users and entities. Followers get personalized feeds that blend streams produced by those followed. The emphasis on recency and relevance, and the highly variable fan-out of the follows graph, make this feature difficult to implement at the scale seen in major social networks.