want to understand to which degree a site is used to make social connections with
others and form communities. This is only possible if people are interacting with
each other directly. The more likely it is that people will meet again, the more likely
it is that they will form social connections, if such connections do not already exist.
For example, reddit has many subforums; some are based on a topic and some are
based on a community, like a university or a town. The smaller the community, the
more likely that people will know or get to know each other.
In some cases, online social networks are a continuation of existing social
relationships in the physical world. They simply allow people who know each other
to communicate. In other cases, they allow new relationships to form under real
or invented identities. For example, in online games, sometimes people interact
with characters they only know within the game context. Generally, online social
networks form around a shared interest, background, point of view or story. Trust
is crucial in some of these sites. They allow people to take actions that are not
otherwise possible (e.g., coordinating massive public demonstrations) and share
private information (e.g., helping people share personal health stories and give
advice to each other anonymously in online forums). Sites like CouchSurfing allow
people to stay in each other's houses when they are traveling. People give micro-
loans to those who need them via sites like Kiva. People collaborate on software
development on sites like Advogato and engage each other in research discussions
on ResearchGate. Entrepreneurs test the demand for new products by Kickstarter
campaigns. All these actions require trust.
A site's design may establish specific reputation mechanisms to help its users.
Some sites allow people to provide explicit trust rankings of each other, which are
then aggregated to a reputation rating. Alternatively, the design may provide an
environment in which people can establish their own rules and behavioral norms.
These norms are enforced by non-verbal [ 77 ] or verbal cues. For example, the well-
publicized reddit etiquettes or reddiquettes are an example of a verbal norm, which
is enforced by messages by others. Free speech is very strongly supported in reddit,
so votes for posts generally imply that the post is relevant to a subreddit. This is
enforced by other redditors who criticize inappropriate behavior in their comments,
e.g., downvoting someone because they do not like a post is not tolerated. If this
does not work, moderator actions are taken.
Research is still ongoing on the topic of whether the Internet provides completely
new norms of behavior and social organizations, or it extends existing patterns in an
incremental way [ 20 ]. One of the fertile areas of study is how people use these sites
to form trust relationships and improve credibility of information, and to verify the
validity of rumors and stop the spread of incorrect information. We will study trust
in information in Sect. 4.3 .Tendetal. [ 4 ] study the trust ratings in different social
media sites. They find that the ratings of people for each other on social media sites
are generally very positive if it is made public who voted how for whom. However,
people are willing to give more candid ratings in private. Hence, any trust algorithm
has to take into account the social and community context for a rating.
The second area of study is to determine who trusts whom and how the trust can
be quantified based on existing social interactions and explicit ratings [ 29 ]. This