Social networks and websites have revolutionized the Internet. Most people online participate in some social network, either it's Facebook, Twitter, Pinterest, GitHub, StackOverflow, or any of the zillion other social networking websites that have sprung up. They're an important way for people to connect and stay in contact, but they're also a major source of data about people's relationships and activities.

Analyzing this data is important for a number of reasons. Of course, advertisers and marketers want to squeeze as much information out of the data as they can. But if you're running the social network, you'll want to analyze the data to figure out what's working and what's falling flat. You want to ask yourself constantly what you can do to engage users better and to make your social network a more compelling, enjoyable, or useful experience for your users.

Over the course of this chapter, we'll get an open data dump from the StackExchange...