Wikipedia gives this information about the history of social networking sites
Early social networking websites started in the form of generalized online communities such as The WELL (1985), Theglobe.com (1994), Geocities (1994) and Tripod.com (1995).
These early communities focused on bringing people together to interact with each other through chat rooms, and share personal information and ideas around any topics via personal homepage publishing tools
User profiles could be created, messages sent to users held on a “friends list” and other members could be sought out who had similar interests to yours in their profiles
Between 2002 and 2004, social networking sites emerged as the most popular sites in the world, causing such sites to become part of mainstream users globally.
Social networking began to flourish as a component of business internet strategy at around March 2005 when Yahoo launched Yahoo! 360°. In July 2005 News Corporation bought MySpace, followed by ITV buying Friends Reunited in December 2005.
It is estimated that combined there are now over 200 social networking sites using these existing and emerging social networking models.
The non-internet alternatives are basically the traditional ways of socialising such as having a conversation face to face.
“ Social Networking has changed and continues to change the way that we socialise every day” according to Joey Bernal December 28, 2009, 08:04 AM - http://www.itworld.com/it-managementstrategy/90619/social-networking-6-things-consider-you-share-it-all
Another non-internet alternative to social networking sites is that of face to face interaction and some people believe that these sites are getting rid of peoples communication skills. “ online networking kills inter-personal skills” this is a quate from Tue, 15/09/2009 - 11:31 — jamesgurd posted on http://www.marketingdonut.co.uk/forum/social-networking-sites-and-the-death-of-inter-personal-skills-