Some time in 2011, there was an earthquake that moderately shook the Northeast United States. Its epicenter was around Washington, DC, and the shockwaves propagated through a large part of the East Coast. While the quake did not produce any substantial damage to people or properties, it was intriguing that, before Bostonians physically felt the tremors, they learned about this event through tweets from the DC area. This is truly an example of information traveling at the speed of light—certainly at a speed faster than an earthquake! If this was written a decade ago, we would be talking about how amazing this phenomenon is—information dissemination through a microblogging site in a manner not previously conceivable. But we live in an era where such instances are a commonplace. The power of the participatory Web, often called the Web 2.0, is realized and practiced by almost everyone connected to the Internet. While it’s not a physically different entity, Web 2.0 reflects a revolutionary mentality in Web users. This new platform, which includes user-driven services and user-generated content, affords us the ability to not only seek and consume information but also to produce and manipulate it. In this chapter, we will see how this new information behavior is manifested through social media and networking services. The chapter will start with a section on social media and a section on social networking, even though at times it’s hard to separate them. Then we will dive deeper into some of the core issues relating to social media/networking, including privacy, identity construction, communication and knowledge sharing, and social capital. The big picture of all our related concepts, along with social media and social networking, is shown in Fig. 3.1.