E-mail, or electronic mail, was one of the first social mediums available to visitors in cyber space. Developed by Ray Tomlinson in 1971, e-mail originally allowed users to only post mail messages to individual accounts across a single network. The supporting software was quickly circulated among the computer sites on ARPANET, a pre-Internet version of the World Wide Web that was used to connect a network of defense department computers. By 1972, e-mail was the most widely used application on the ARPANET network. Ever since, e-mail has been the most powerful and popular of all social computing software.

By the year 1999, the heyday of the Internet, over 610 billion e-mails were sent worldwide. E-mail can be read and sent from a network computer, across even the very slowest of modem connected web links. It is so basic to modern computing that, for almost all Internet users, it is the first thing they check when they log on to their computer. E-mail has been widely credited with fueling the surge in Internet usage as many people have sought online access first as a way to access electronic communications with friends, family and colleagues. According to statistics gathered in a study conducted by the University of California in Los Angeles, well over 80 percent of Internet users utilize e-mail at least once a day.

Despite the enduring popularity of e-mail, there have been relatively few attempts to create a map that tracks the structure and content of e-mail. Interfaces for e-mail clients are much the same today as they were a decade ago. Appropriately for a predominantly text-based form of communication, messages are stored in sorted lists and arranged in folders. And yet there is an ever increasing need for better and more efficient tools to manage the seemingly unlimited growth in the volume and importance of e-mails that many people receive on a daily basis.

The power of e-mail for one-to-one communication can easily be used for one-to-many interactions, as well as many-to-many conversations. This is achieved via the use of mailing lists, list servers, and bulletin boards. A mailing list is a one-to-many communication medium where the list owner can send a single message to every member on a list. A message can therefore be delivered to hundreds of subscribers with no extra effort.

A list server extends this concept to allow many-to-many conversations by permitting all subscribers to post messages to everyone on this list. This allows for ongoing discussions involving many participants. Bulletin boards, similarly, allow many-to-many communications between individuals. However, unlike mailing lists, messages are not redistributed to subscribers; instead, messages are posted to a central site, usually web-based, which users have to log on to in order to receive their messages.