In many households today, broadband Internet connections are used not only for e-mail and Web browsing, but also to stream music and video, play online games and/or perhaps make voice calls using a VoIP (Voice over Internet Protocol) service.
You may have several PCs on your home network, as well as some combination of a gaming console like the Xbox 360, an iPhone or other handheld device, and perhaps a streaming music player such as the Squeezebox or a streaming video player such as the Roku...