The document discusses various online social networks and their uses for business purposes. It notes that LinkedIn is a professional networking site launched in 2003 with 40 million users across 170 industries. It also mentions that Facebook was founded in 2004, allows users aged 13 and older, and has been banned in Syria and Iran. Finally, it provides tips for using social media for business, including keeping content simple, using available resources, and not being afraid to make mistakes.