Creating social groups is one of the original practices on the Internet.
Extending back to the 1960's, people have consistently used online tools to expand, extend, re-invent, and build social groups. Today, social networking (sometimes abbreviated SNS, for Social Networking Service)
has become a major activity online, and many of the functionalities and traditions from decades ago have become cast in different interfaces that include features such as profiles, friend and relationship links, instant messaging, blogs, bookmark-sharing, Web-based discussions, and Web-based email.
Facebook: originated as a way for college students to get to know each other.
google+: Google's entry into social networking, full released November 2011.
Linkedin: a professionally-oriented network used to build business and professional contacts or to get in touch with past colleagues and friends.
MySpace: a social network based on user profiles as well as many other tools to build relationships, communication, and interaction.
Friendster: a pioneering social network recognized as the first (Web-based) social networking site.
Classmates: originated as a way for high-school classmates to keep in touch.
Ning.com: lets you create your own social network.
yelp.com: a network of people reviewing local restaurants, shopping, nightlife, businesses, and other places. Friend relationships, favorites, and profiles support a range of member-to-member interaction.
ResearchGATE: social networking for scientists and researchers to connect with like-minded researchers, discuss and collaborate in groups or share papers and resources
Meetup.com: a social network that aims to connect people through in-person, local meetings on a variety of interest topics.
outside.in: tracks news, views, and conversations in towns and neighborhoods; individual profiles
Blogging: Creating diary-like commentary on life, passing events, people, and ideas has found a form in blogs.
Social networks emerge as groups of bloggers work and
comment on blogs or make hypertext links from blog to blog.
Many social networks that are based on user profiles also include blogs as part of the services they offer to users.
Bookmarking: Information-sharing can be among a group of people using social networking sites. Altough sharing interesting sites online has been an activity for several decades, these social networking sites oriented to tagging or bookmarking bring it to a more visible, organized, and efficient level.
Personal Ads: With social networks come social attractions, so it follows that many networks develop specifically for dating. Extending the ancient concept of "computer dating" beyond just matching characteristics like age and preferences for long walks on the beach, personal ad services today provide matching based on personality testing, some of which is based on research.