Here Social Network Advisor lists the sites it mentions in its content pages, as well as other well-known social networking sites. Some sites are primarily social networking sites, while others are geared towards other kinds of specific content but have social networking qualities to them.

So what defines an online social network? This site considers true social networking sites to be sites designed for sharing users’ profiles, making virtual friendships or connections with others, and simulating social interaction, including sharing media. Sites for sharing blogs or media undoubtedly take on many qualities of social networking sites, but they should not be expected to compare to social networking sites in the same ways.

Even basic statistics like the below information is vital to analyzing social networking sites in proper context. To assess a site’s success or safety, an analyst must be familiar with the amount of time a site has had to grow, what core audience it designs its interface and features around, the site population and traffic it must accommodate on its servers, and the other big sites that it competes with. Social Network advisor provides all of this data in the following charts.

Social networking sites:

Website	Date started	Number of profiles, May 2007	Core audience	Principles	Location	Ownership
	November 2003	175+ million	Musicians, teens, young adults, entertainers	Friendship, networking, multimedia, customizability	Beverly Hills, CA	News Corporation / Fox Interactive Media
	February 2004 (Opened to public September 2006)	25+ million	U.S. college students, high school students, young professionals	User networks, privacy, information access	Palo Alto, CA	Facebook, Inc.
	January 2004 (invitation only)	50+ million	Users in Brazil and India	Making new friends, maintaining existing relationships	(Google) Mountain View, CA	Google
	December 2004 (as MSN Spaces)	120+ million	MSN and Windows Messenger users	blogging, publishing photos, messaging	Redmond, WA	Microsoft / Windows Live
	March 2005	5 million	Yahoo! users	Sharing blogs, photos, reviews	Sunnyvale, CA	Yahoo!
	1995	40+ million	U.S & Canada school/college alumni, work networks	Friends, communities, announcements, reunions	Renton, WA	United Online, Inc
	2003	11+ million	Business professionals	Business connections, job search	Mountain View, CA	LinkedIn Corporation

• MySpace has faced both praise and criticism for allowing its users to edit the HTML of their profile pages. This feature is so popular that hundreds of external websites exist solely to provide users with graphics, forms, tools, and games to add to their profile. Yet the vast majority of users who modify their HTML do so by copying and pasting code, not by professional design, so a single page might be filled with dozens of ill-formed tags and overloaded with external media, which is an inconvenience to users requiring screen readers or with slow Internet connections.
• MySpace began as a site for sharing public information about oneself and promoting bands and music groups, and thus profiles on the site are public by default. But after criticism and public attention, MySpace decided to have give users of age 14 or 15, the minimum age, private profiles by default to prevent information abuse and online predation.
• Facebook has followed a profile model of privacy from the start, restricting profile access to users of the same network, such as the same college or region. Given this restraint and the ability of users to choose what information and media they share, the site’s founder Mark Zuckerberg ultimately envisions a site where any accessible information is free and easy to find, and the site designed somewhat controversial features such as the News Feed after this goal.

Blog community sites:

Website	Date started	Number of blogs, May 2007	Core audience	Principles	Location	Ownership
	1998	40+ million	Teenagers, personal journals, book and media reviews	Sharing blogs, photos, blog ratings, metros	New York, NY	Xanga.com Inc.
	1999	13 million	Teenagers, bloggers, writers, popular in Russia	Journals, friends, group journals	San Francisco, CA	Six Apart Ltd.
	1999	unknown	Users in Brazil and India	Professional, organized, integrated with Google features	(Google) Mountain View, CA	Google

• While they are primarily designed for creating and sharing personal weblogs, not for making social connections, popular weblog sites such as these still can face issues of user privacy and security. A quick glance at Xanga’s home page, for example, shows it is vigilant about educating its users about web safety.
• LiveJournal’s journal community feature is an effective model for social-network quality information sharing on a blog site. Giving the users to post fully-functional weblog entries publicly or privately on their own journal or a community journal gives them fully flexibility and convenience of information sharing. LiveJournal’s successful communities range from regional and school-based groups to hobbies such as fanfiction writing and knitting.
• The community-oriented nature of blog sites such as these can also be demonstrated with their potential to create information bubbles. Bloggers often affiliate predominantly or exclusively with other blogs with the same political or social views. An information bubble is when such a group of bloggers tends to support and extremize rather than moderate their views.

Multimedia sites:

Website	Date started	Number of users, May 2007	Core audience	Principles	Location	Ownership
	February 2005	22+ million	Amateur and professional filmmakers, home videos, music and entertainment sharing	"Broadcast yourself", rating and tagging videos	San Bruno, CA	Google
	February 2004	4 million	Personal photographs, photographers, bloggers	Tagging and browsing photos	Sunnyvale, CA	Yahoo!

• While Facebook has the largest stake in the online photo sharing market, Flickr is one of the largest sites where photos can be shared publicly and be searched. It has nearly a billion photos uploaded, surpassing the 250 million mark in September 2006. Flickr allows its users to give their photos descriptive and geographic tags, and form photo-sharing groups based on artistic or social interests. It has features of a social networking site and a strong community of artists and photographers, but is ultimately a photo-sharing site.
• YouTube is currently the most highly successful video sharing site on the Internet, with 100 million videos viewed each day in August 2006 when Google bought the site. While it is focused on video sharing, it allows users to register, comment on each others’ videos, and potentially form communities based on shared interests, all qualities of social networking sites. A user can browse video by tag words, by the member who uploaded it, or by a channel such as humor or music. Members who upload successful videos can even share the site’s ad revenue, giving users incentive to upload high-quality, high-traffic original video clips. The site has faced criticism and lawsuit for containing vast amounts of copyrighted material, but since the Google acquisition, it has been proactively monitoring new uploads for such material.