A social network is a social structure composed of individuals, groups, or organizations linked by values, visions, ideas, financial exchange, friendship, kinship, conflict, or trade.

Social networking refers to activities performed using social software tools (e.g., blogging) or social networking features (e.g., media sharing).

A social network can be described as a map of all relevant links or connections among the network’s members. For each individual member that map is his or her social graph. Mark Zuckerberg of Facebook originally coined this term to refer to the social network of relationships among users of Facebook.

The idea was that Facebook would take advantage of relationships among individuals to offer a richer online experience.

Social networks can also be used to determine the social capital of individual participants. Social capital refers to the number of connections a person has within and between social networks.

Participants congregate on social networking Web sites where they can create their own profile page for free and on which they can write blogs and wikis; post pictures, videos, or music; share ideas; and link to other Web locations they find interesting.

Social networkers chat using instant messaging and Twitter, and they tag posted content with their own keywords, making content searchable and facilitating interactions and transactions.

Social networkers converse, collaborate, and share opinions, experiences, knowledge, insights, and perceptions with one another.

They also use these Web sites to find like-minded people online, either to pursue an interest or a goal or just to establish a sense of community among people who may never meet in the real world.

Socially oriented

Socially focused public sites, open to anyone

• Facebook (www.facebook.com)
• Google Orkut (www.orkut.com)
• Google1 (https://plus.google.com)
• Hi5 (www.hi5.com)

Professional networking

Focused on networking for business professionals

• LinkedIn (www.linkedin.com)

Media sharing

• Netcasting includes podcasting (audio) and videocasting (audio and video). For example, educational institutions use netcasts to provide students with access to lectures, lab demonstrations, and sports events. In 2007, Apple launched iTunes U, which offers free content provided by major U.S. universities such as Stanford and MIT.
• Web 2.0 media sites allow people to come together and share user-generated digital media, such as pictures, audio, and video.
  $\quad$º Video (Amazon Video on Demand, YouTube, Hulu, Facebook)
  $\quad$º Music (Amazon MP3, Last.fm, Rhapsody, Pandora, Facebook, iTunes)
  $\quad$º Photographs (Photobucket, Flickr, Shutterfly, Picasa, Facebook)

Communication

• Blogs: Blogger, LiveJournal, Open Diary, TypePad, WordPress, Vox, Expression Engine, Xanga
• Microblogging/Presence applications: Twitter, Plurk, Tumblr, Yammer, Qaiku

Collaboration

• Wikis (Wikimedia, PBworks, Wetpaint)

Social bookmarking (or social tagging)

Focused on helping users store, organize, search, and manage bookmarks of Web pages on the Internet

• Delicious (www.delicious.com)
• StumbleUpon (www.stumbleupon.com)
• Google Reader (http://reader.google.com)
• CiteULike (www.citeulike.com)

Social news

Focused on user-posted news stories that are ranked by popularity based on user voting

• Digg (www.digg.com)
• Chime.in (http://chime.in)
• Reddit (www.reddit.com)

Events

Focused on alerts for relevant events, people you know nearby, etc.

• Eventful (www.eventful.com)
• Meetup (www.meetup.com)
• Foursquare (www.foursquare.com)

Virtual meeting place

Sites that are essentially three-dimensional worlds, built and owned by the residents (the users)

• Second Life (www.secondlife.com)

Interesting New Social Networks

• Empire Avenue (www.empireavenue.com) is a social exchange network where members invest virtual currency in people and brands that interest them.
• Color (www.color.com) is a free mobile app that creates an instant social network based on users’ locations and proximity to others. Users can instantly share images, videos, and text conversations with others nearby.
• Foursquare (http://foursquare.com) is a location-based mobile service that enables participants to share their location with friends by checking in via a smartphone app.
• Hunch (www.hunch.com) maps people’s interests by asking them a series of questions. The site creates a “taste graph,” which tracks everything that a user likes and dislikes.

Online Marketplaces for Microjobs

• For example, TaskRabbit (www.taskrabbit.com) and Zaarly (www.zaarly.com) enable people to farm out chores to a growing number of temporary personal assistants. Thousands of unemployed or underemployed workers use these sites. The parttime or full-time tasks are especially popular with stay-at-home moms, retirees, and students. Workers choose their jobs and negotiate their own rates.