Flash: A program that lets users create animation for the Web.
Blog: A portmanteau combining Web and log. It is a user- generated Web site on which entries often are journal-style and provide news or the writer's commentary on a topic.
Blogosphere: The term that refers to the social network of all blogs on the Internet.
Facebook: A social networking site that initially was limited to college students but was extended to the general public in September 2006. As of July, Facebook had 47 million users.
Mashup: A Web site or application that combines content from more than one source into an integrated experience.
MySpace: A general-interest, social-networking site. As of September 2007 it had more than 200 million global users.
Podcast: A digital file that is distributed over the Internet via syndication feeds. It is designed for playback on MP3 players.
Social Networks: Internet applications that help connect friends, business partners or other individuals using a variety of tools. Examples of online social networks are MySpace, Facebook, Friendster and LinkedIn.
Virtual World: A computer-based simulated environment intended for its users to inhabit and interact via avatars.
Web 2.0: Term coined by O'Reilly Media in 2004 used to describe the Internet applications that arose amid the ashes of the dot-com collapse. Particular focus has been given to user-created content, lightweight technology, service-based access and shared-revenue models.
Wiki: A type of Web site that allows visitors to easily add, edit and remove content. The term wiki also can refer to the collaborative software itself.
Sources: Gartner, O'Reilly Media, Wikipedia, TowerGroup