Before social media, most communication was either mainly private and one-to-one (e.g. letters or the telephone), or public broadcasting (e.g. radio, TV, newspapers). By contrast, social media is mainly devoted to groups, and allows us to scale different sizes of audience and degrees of privacy.

Chile
In this film we can see how Instagram became a key site of community solidarity after an earthquake; it became a place where people tried to convey their experience of disaster and marginalisation to a larger audience.
India
Social media has equally become an integral part of relationships within established groups, including the family.
England
People in the village provided several examples of how new groups on social media were more effective than traditional groups such as the church or one's neighbours.
Story
Neighbours vs dog walkers

Rural China
Here social media is used both to consolidate established 'circles' of friends, but is also a means for contacting strangers on the basis of common interests.
Italy
While social media is used by groups, these tend to be multiple, unstable and overlapping, with the exception of family groups.

Trinidad
Social media is useful for the recombination of people representing different kinds of relationships, such as family, friends and work colleagues.

Industrial China
While here, as in the previous examples, social media is important for consolidating groups of similar people, it rarely seems to cross the boundaries between these groups.