This document discusses various social media and online networking platforms. It provides information on Facebook as a social networking service started in 2004 by Mark Zuckerberg for personal profiles and messaging between friends. It also describes Wikipedia as a free, open-content online encyclopedia owned by the Wikimedia Foundation, and Twitter as a microblogging service allowing users to send and read short 140-character messages. Finally, it mentions Google+ as a social network launched by Google in 2011.