How Twitter Decides What to Place in Your Stream

Twitter began adding content to users’ timelines, and it says it’s going to keep doing that.

Sources familiar with the update say Twitter’s algorithm searches for popular tweets in your “social graph,” marked by actions like favorites and retweets. But it’s not showing you those tweets specifically because of one of your pal’s actions -- it’s showing it to you because lots of your pals have shown interest in that tweet.