Social networks are social structures made up of individuals and relationships between them. A social network perspective models how social structures influence variables and change over time. The study of social networks uses social network analysis to identify influential people, structures, and dynamics. Social networking services are online platforms that focus on building social networks by allowing users to share interests and activities through profiles and interaction features. Popular social networks now combine categories, friend connections, and trust-based recommendations.

1. A social network is a social structure made up of a set of actors (such as individuals or organizations)
and the dyadic ties between these actors (such as relationships, connections, or interactions). A social
network perspective is employed to model the structure of a social group, how this structure influences
other variables, or how structures change over time.[1] The study of these structures uses methods
in social network analysis to identify influential nodes, local and global structures, and network dynamics.
Social networks are distinct from information, biological, or electrical networks, but theories and methods
generalizing to all of these complex networks are studied in the field of network science.[2][3]
Social networks and the analysis of them is an inherently interdisciplinary academic field which emerged
from social psychology, sociology, statistics, and graph theory. Jacob Moreno is credited with developing
the first sociograms in the 1930s to study interpersonal relationships as structures in which people were
points and the relationships between them were drawn as connecting lines. These approaches were
mathematically formalized in the 1950s and theories and methods of social networks became pervasive in
the social and behavioral sciences by the 1980s.[1][4]
A social networking service is an online service, platform, or site that focuses on building and reflecting
of social networks or social relations among people, who, for example, share interests and/or activities
and people with similar or somewhat similar interests, backgrounds and/or activities make their own
communities. A social network service consists of a representation of each user (often a profile), his/her
social links, and a variety of additional services. Most social network services are web-based and provide
means for users to interact over the Internet, such as e-mail and instant messaging. Online
community services are sometimes considered as a social network service, though in a broader sense,
social network service usually means an individual-centered service whereas online community services
are group-centered. Social networking sites allow users to share ideas, activities, events, and interests
within their individual networks.
The main types of social networking services are those that contain category places (such as former
school year or classmates), means to connect with friends (usually with self-description pages), and a
recommendation system linked to trust. Popular methods now combine many of these,
with Facebook, Google+ and Twitter widely used worldwide, The Sphere (luxury
network), Nexopia (mostly in Canada);[1] Bebo,[2] VKontakte, Hi5, Hyves (mostly in The
Netherlands),Draugiem.lv (mostly in Latvia), Ask-a-peer (career oriented), StudiVZ (mostly in
Germany), iWiW (mostly in Hungary), Tuenti (mostly in Spain), Nasza-Klasa (mostly in
Poland), Decayenne, Tagged, XING,[3] Badoo[4] and Skyrock in parts of Europe;[5] Orkut and Hi5 in South
America and Central America;[6] and Mixi, Multiply, Orkut, Wretch, renren and Cyworld in Asia and the
Pacific Islands and Facebook are very popular in India.
Another form of Social Network has been introduced by airlines that allows passengers to meet others
who share their interests before their flight so that seating may be pre-arranged. [7]
Features
[edit]Typical features
Social networking sites (SNSs) share a variety of technical features. The most basic of these are visible
profiles with a list of "friends" who are also users of the site. In an article entitled "Social Network Sites:
Definition, History, and Scholarship," Boyd and Ellison adopt Sunden's (2003) description of profiles as
unique pages where one can "type oneself into being."[29] A profile is generated from answers to

2. questions, such as age, location, interests, etc. Some sites allow users to upload pictures, add multimedia
content or modify the look and feel of the profile. Others, e.g., Facebook, allow users to enhance their
profile by adding modules or "Applications."[29] Many sites allow users to post blog entries, search for
others with similar interests and compile and share lists of contacts. User profiles often have a section
dedicated to comments from friends and other users. To protect user privacy, social networks typically
have controls that allow users to choose who can view their profile, contact them, add them to their list of
contacts, and so on.
[edit]Additional features
Some social networks have additional features, such as the ability to create groups that share common
interests or affiliations, upload or stream live videos, and hold discussions in forums. Geosocial
networking co-opts Internet mapping services to organize user participation around geographic features
and their attributes.
There is a trend towards more interoperability between social networks led by technologies such
as OpenID and OpenSocial. Lately, mobile social networking has become popular.[citation needed] In most
mobile communities, mobile phone users can now create their own profiles, make friends, participate in
chat rooms, create chat rooms, hold private conversations, share photos and videos, and share blogs by
using their mobile phone. Some companies provide wireless services that allow their customers to build
their own mobile community and brand it; one of the most popular wireless services for social networking
in North America is Facebook Mobile.
An online community is a virtual community that exists online and whose members enable its existence
through taking part in membership ritual. An online community can take the form of an information system
where anyone can post content, such as a Bulletin board system or one where only a restricted number of
people can initiate posts, such as Weblogs. Online communities have also become a supplemental form
of communication between people who know each other primarily in real life. Many means are used
in social software separately or in combination, including text-based chat rooms and forums that use
voice, video text or avatars. Significant socio-technical change may have resulted from the proliferation of
such Internet-based social networks.[1]
Classifying online communities
A number of authors have looked at classifying online communities and those within them to better
understand how they are structured. It has been argued that the technical aspects of online communities,
such as whether pages can be created and edited by many, as is the case with Wikipedia, or whether
only certain users can post entries and edit them, as is the case with most weblogs, can place specific
online communities into types of genre.[11]
Some research has looked at the particular users of online communities. Amy Jo Kim has classified the
rituals and stages of online community interaction and called it the 'Membership life cycle'.[12] Clay Shirky
talks about community of practice whose members collaborate and help each other in order to make
something better or improve a certain skill. What makes these communities bond is "love" of something
as demonstrated by members who go out of their way to help without any financial interest. [13] Others
have suggested character theories to break particular patterns of behavior of particular users into certain
categories.[14][15][16]

3. Some of the most successful online communities are those whose members have positively invested
positive approaches to posting and carrying on conversations in forums and chatrooms. Online
communities are used to chat and partake on a virtual social network.