Social media is having three main impacts on news: 1. It provides a new channel for distributing traditional news content, although people primarily share and engage with topics they like rather than brands or editors' choices. 2. Social media itself has become a new source of news, as events can spread virally before traditional media reports on them. 3. Social media is enabling new models of participatory news where audiences both consume and create news, as seen in news startups that rely heavily on social platforms for traffic and content.