The document discusses the rise and use of online social networks for business and marketing purposes. It defines social networks as online spaces where users can create profiles, connect with others, and share information publicly or privately. Examples provided include Facebook, MySpace and LinkedIn. The document also examines network mechanics like Metcalfe's Law and Reed's Law that cause networks to grow exponentially as more users join. Lastly, it provides tips on developing a social media strategy and etiquette for businesses and individuals using networks for networking, marketing and communication.