Although the roots of social media took hold at the very end of the 20th century, social media is really a 21st century phenomena, since we are still in the midst of a global explosion of its ramifications.
In a nutshell, social media is stuff you and I create and publish. Whether that might be articles, photos, videos, music, audio broadcasts, or anything else we care to publish on the web.
The term “social media” is used to draw a distinction between “traditional media”, which might also be characterized as “broadcast” or “mass” media.
Social media is you and I, and anyone else, creating information and publishing it for others to check out.
Traditional media is from organizations that have been the primary source of information since the first printing press. Of course the power of owning a printing press blossomed into the gigantic book, newspaper, magazine, radio, and TV outlets that have traditionally been the source of what populations have had access to for information.
Underlying the application of social media is the ongoing development of technology, which has transformed people from content consumers to content producers, or publishers.
Some examples of social media applications include blogs, Internet forums, Twitter, Facebook, LinkedIn, MySpace, FriendFeed, Yahoo! Groups, Wikipedia, Delicious, StumbleUpon, Google Reader, Digg, Mixx, Reddit, Yelp, Flickr, Photobucket, YouTube, Vimeo, Revver, Skype Blip.fm, Last.fm, epinions.com, Yahoo! Answers, WikiAnswers and way too many more to list, as well as more being developed every day.