WHAT IS SOCIAL MEDIA?
Social Media is an umbrella term used to describe the various forms of new media rapidly being adopted around the globe by businesses, organizations and individuals whose websites and services integrate new technologies, social interaction and rich media like audio, hyperlinked text, images and video.

Some examples are blogs, podcasts, social-networking sites like facebook and linkedin, wikis, and media sharing sites like Youtube. You can read more on here on Wikipedia, a type of social media itself, if you'd like to dive into it some more.