This document summarizes Class 2 of a social media marketing course. It discusses the "big three" social networks - Facebook, LinkedIn, and Twitter. For each network, it provides background information, member demographics, traffic trends, etiquette guidelines, and strategies for using the networks. It also lists 9 actions companies can take on each network, such as updating statuses, following competitors, sharing content, and connecting with customers. The class ends with assigning homework to engage with one of the social networks.