Social network systems are significant scaffolds for political, economic, and sociocultural change. This is in part due to the widespread availability of sophisticated network technologies and the concurrent emergence of rich media Web sites. Social network sites provide new opportunities for social-technological research. Since we can inexpensively collect electronic records (over extended periods) of social data spanning diverse populations, it is now possible to study social processes on a scale of tens of million individuals. To understand the large-scale dynamics of interpersonal interaction and its outcome, this article links the perspectives in the humanities for analysis of social networks to recent developments in data intensive computational approaches. With special emphasis on social communities mediated by network technologies, we review the historical research arc of community analysis as well as methods applicable to community discovery in social media.