Social TV usually refers to the use of social media platforms to enrich the experience of consuming a TV program and to possibly extend his audience.
Social TV encompasses:
use of social networks to announce and promote a TV program before broadcasting
use of social media to bring interactivity in TV programs
to give an echo to program before, during and after the broadcasting (by promoting the use of a Twitter hashtag for instance)
use of social media to reinforce TV ads (see social TV ad targeting)
Twitter is considered as the dominant social network for social TV due to the possibility of using hashtag for accessing in real time all tweets about a program.
A part of social TV phenomenon is due to spontaneous behaviors of viewers and another is due to marketing strategies of channels, productors and entertainers.
Social TV is tied to second screen phenomenon, but second screen applications are not always in social TV domain.
There is a debate about the fact that second-screen usage during TV viewing may impact positively or negatively audience engagement. It’s an important question for both TV producers and advertisers.
An example of an australian neuro-science study claiming a positive influence on engagement: