Social TV refers to using social media like Twitter to discuss TV show content as it airs. Hashtags on Twitter helped drive social discussion about TV starting in the late 2000s. The "second screen" of smartphones and tablets allows companion usage while watching TV. Twitter is a major platform for social TV discussion, with 66% of users tweeting about shows and 95% of TV chatter occurring on Twitter. Social engagement through hashtags can increase viewership. Apps like GetGlue and analytics companies measure social TV interactions and conversations to quantify audience engagement with shows. The future of social TV may include more integrated apps and rewards for non-linear viewing.