Front Channel - The Front Channel refers to the actual broadcast from the television network operator to the TV viewer.  This broadcast faces the viewer. It's one-way in nature. In non-interactive TV systems, the front channel often is the only channel, as the signal or data stream is only going to the viewer and the viewer has limited ability to interact with the data they're receiving. But in interactive TV, a back channel is employed for the return flow of data from the end-user (viewer) to the network operator.

See the Interactive Television Institute.